Bias control method for modulator, and related device

Abstract

Provided in the embodiments of the present application are a bias control method for a modulator, and a related device, which can effectively improve the precision and efficiency of controlling a bias point of a modulator at a target bias point without causing crosstalk to a service. The method comprises: a bias controller sending a bias control signal to a modulator, the bias control signal comprising a bias signal and a target signal, wherein the target signal is obtained by means of superimposing a disturbance signal onto the bias signal, the modulator receives the bias signal within a time period in which the modulator outputs a service signal, while the modulator receives the target signal within a time period in which the modulator outputs a detection signal, and the detection signal is used for controlling a bias point of the modulator at a target bias point.

Description

A modulator bias control method and related equipment

[0001] This application claims priority to Chinese Patent Application No. 202510495913.3, filed on April 18, 2025, entitled "A bias control method and related equipment for a modulator", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of optical communication technology, and in particular to a modulator bias control method and related equipment. Background Technology

[0003] In applications such as optical sensing and optical communication, modulators are used to modulate optical signals. For example, modulators can be Mach-Zehnder modulators (MZM), in-phase and quadrature Mach-Zehnder modulators (IQ-MZM), dual-polarization in-phase and quadrature Mach-Zehnder modulators (DP-IQ-MZM), etc.

[0004] Taking MZM as an example, a bias voltage is applied to the modulator to make it work at the target bias point. The modulator working at the target bias point modulates the service electrical signal onto the optical signal to output the modulated optical signal. The target bias point where the modulator works determines the phase difference of the output optical signal. For example, the target bias point can be the minimum transmission (null) point, the maximum transmission (peak) point, the quadrature (+quadrature, +quad) point, or the negative quadrature (-quadrature, -quad) point. However, modulators are susceptible to crosstalk from external factors such as temperature and environment, which can cause the relationship between the bias voltage and the target bias point to shift. For example, the bias voltage applied to the modulator may cause it to not operate at the null point. To address this, a sinusoidal perturbation signal can be applied to the modulator. This perturbation signal is a small-amplitude signal that can fine-tune the bias voltage applied to the modulator. By detecting changes in the optical signal output by the modulator through the perturbation signal, the bias voltage can be adjusted so that the adjusted bias voltage controls the modulator to operate at the null point.

[0005] However, the disturbance signal can cause crosstalk to the service signal. To reduce the crosstalk of the disturbance signal to the service signal, the amplitude of the disturbance signal needs to be reduced, but this will reduce the efficiency and accuracy of controlling the modulator's bias point at the target bias point. Summary of the Invention

[0006] This application provides a modulator bias control method and related equipment, which can effectively improve the accuracy and efficiency of controlling the modulator bias point at the target bias point without causing crosstalk to services.

[0007] In a first aspect, embodiments of this application provide a bias control method for a modulator. The method includes: a bias controller sending a bias control signal to a modulator. The bias control signal includes a bias signal and a target signal. The target signal is obtained by superimposing a perturbation signal onto the bias signal. The target signals appear at intervals in the bias control signal. For example, the bias control signal includes K target signals, where K is any integer greater than 1. There is a time interval between any two adjacent target signals among the K target signals. Specifically, the bias control signal loaded onto the same branch of the modulator includes a bias signal without superimposed perturbation signals, and target signals with superimposed perturbation signals on the bias signal. The bias signal without superimposed perturbation signals and the target signals with superimposed perturbation signals appear in the bias control signal in a time-division manner. During the time period when the modulator outputs a service signal, the modulator receives the bias signal. During the time period when the modulator outputs a detection signal, the modulator receives the target signal. The detection signal is used to control the bias point of the modulator at the target bias point.

[0008] As shown in this aspect, in one bias control signal sent by the bias controller to the modulator, the bias signal (without superimposed perturbation signal) and the target signal (with perturbation signal superimposed on the bias signal) appear in a time-division manner. This causes the modulator to output service signals and detection signals in a time-division manner, ensuring that the service signal corresponding to the bias signal and the detection signal corresponding to the target signal appear in the modulated optical signal output by the modulator in a time-division manner, effectively avoiding crosstalk between the detection signal and the service signal. The bias signal (without superimposed perturbation signal) sent by the bias controller to the modulator is used to enable the modulator to perform service modulation. The target signal (with perturbation signal superimposed on the bias signal) sent by the bias controller to the modulator is used to detect whether the modulator's bias point is controlled at the target bias point. That is, it detects whether the modulator's bias point has deviated from the target bias point and detects the degree of deviation. Since the bias signal (without superimposed perturbation signal) and the target signal (with perturbation signal superimposed on the bias signal) appear in the bias control signal in a time-division manner, crosstalk caused by the target signal to the service modulation is avoided, while the amplitude of the target signal can be increased, thereby improving the accuracy and efficiency of controlling the modulator's bias point at the target bias point.

[0009] Based on the first aspect, in one optional implementation, there is a time interval between the time period during which the modulator outputs the service signal and the time period during which it outputs the detection signal. Specifically, there is a time interval between the time period during which the bias controller sends the bias signal (without superimposed perturbation signal) to the modulator and the time period during which it sends the target signal (with perturbation signal superimposed on the bias signal). For example, the bias controller sends the bias signal to the modulator during the service time period; the bias controller sends the target signal to the modulator during the perturbation time period, wherein there is a time interval between the perturbation time period and the service time period.

[0010] In this implementation, there is a time interval between the time period during which the bias controller sends the bias signal (without superimposed perturbation signal) to the modulator and the time period during which the target signal (with perturbation signal superimposed on the bias signal) is sent. This avoids crosstalk caused by the target signal to the process of modulating the service electrical signal onto the optical signal, effectively reducing the bit error rate. It also effectively avoids the mixing of the service electrical signal and the target signal sent to the modulator. While avoiding crosstalk caused by the target signal to the service modulation, it can increase the amplitude of the target signal, thereby improving the accuracy and efficiency of controlling the bias point of the modulator at the target bias point.

[0011] Based on the first aspect, in an optional implementation, the bias signal includes a first bias signal, the bias control signal includes a first bias control signal, and the bias controller sending the bias control signal to the modulator includes: the bias controller sending the first bias control signal to a first branch of the modulator, the first bias control signal including the first bias signal, a first target signal, and a second target signal, wherein the first target signal is obtained by superimposing a first disturbance signal on the first bias signal, the second target signal is obtained by superimposing a second disturbance signal on the first bias signal, and the polarity of the voltage of the first disturbance signal is opposite to the polarity of the voltage of the second disturbance signal.

[0012] By adopting this implementation method, since the polarity of the first disturbance signal voltage is opposite to that of the second disturbance signal voltage, the first target signal and the second target signal obtained by superimposing the first disturbance signal and the second disturbance signal with the first bias signal can accurately detect whether the bias point of the first branch has shifted from the first target bias point and the degree of shift, thus ensuring the reliability and accuracy of controlling the bias point of the first branch at the first target bias point.

[0013] Based on the first aspect, in one optional implementation, the voltage of the first target signal is the sum of the voltage of the first bias signal and the voltage of the first disturbance signal, and the voltage of the second target signal is the sum of the voltage of the first bias signal and the voltage of the second disturbance signal.

[0014] In this implementation, the bias controller obtains the sum of the first bias signal voltage and the first disturbance signal voltage to superimpose the first disturbance signal onto the first bias signal to obtain the first target signal. The bias controller also obtains the sum of the first bias signal voltage and the second disturbance signal voltage to superimpose the second disturbance signal onto the first bias signal to obtain the second target signal. Based on the first target signal and the second target signal, the bias controller can accurately detect whether the bias point of the first branch has shifted from the first target bias point and the degree of shift, thus ensuring the reliability and accuracy of controlling the bias point of the first branch at the first target bias point.

[0015] Based on the first aspect, in one optional implementation, between the time intervals of two adjacent service signals output by the modulator, the modulator receives at least one of the following:

[0016] At least one of the first target signals, or at least one of the second target signals.

[0017] Using this implementation, the first target signal and the second target signal can be flexibly sent to the first branch of the modulator, improving the flexibility of sending disturbances to the first branch of the modulator.

[0018] Based on the first aspect, in one optional implementation, the voltage of the first disturbance signal remains unchanged during the duration of the first disturbance signal, the voltage of the second disturbance signal remains unchanged during the duration of the second disturbance signal, and the absolute value of the voltage of the first disturbance signal is equal to the absolute value of the voltage of the second disturbance signal.

[0019] By adopting this implementation method, when the absolute value of the first disturbance signal voltage is equal to the absolute value of the second disturbance signal voltage, the accuracy of controlling the bias point of the first branch of the modulator at the first target bias point can be effectively improved.

[0020] Based on the first aspect, in an optional implementation, the method further includes: the bias controller sending a second bias signal to a second branch of the modulator, wherein the second branch receives the second bias signal during both the time period during which the modulator outputs the service signal and the time period during which the modulator outputs the detection signal.

[0021] In this implementation, the bias controller sends a second bias signal to the second branch during the time period of sending the first target signal to the first branch, and also sends a second bias signal to the second branch during the time period of sending the second target signal to the first branch. That is, only the first target signal and the second target signal sent to the first branch are subjected to a small-amplitude perturbation (i.e., the voltage of the first perturbation signal and the voltage of the second perturbation signal), avoiding crosstalk to controlling the bias point of the first branch to the first target bias point due to the small-amplitude perturbation sent to the second branch. This effectively improves the accuracy and efficiency of controlling the bias point of the first branch to the first target bias point.

[0022] Based on the first aspect, in one optional implementation, the bias signal includes a second bias signal, the bias control signal includes a second bias control signal, and the bias controller sending the bias control signal to the modulator includes: the bias controller sending the second bias control signal to a second branch of the modulator, the second bias control signal including the second bias signal, a third target signal, and a fourth target signal, the third target signal being obtained by superimposing a third perturbation signal on the second bias signal, and the fourth target signal being obtained by superimposing a fourth perturbation signal on the second bias signal, wherein the time period during which the bias controller sends the first target signal to the first branch at least partially overlaps with the time period during which it sends the third target signal to the second branch, and the time period during which the bias controller sends the second target signal to the first branch at least partially overlaps with the time period during which it sends the fourth target signal to the second branch.

[0023] In this implementation, when the time period during which the bias controller sends the first target signal to the modulator at least partially overlaps with the time period during which it sends the third target signal, and when the time period during which the bias controller sends the second target signal to the modulator at least partially overlaps with the time period during which it sends the fourth target signal, it can accurately detect whether the bias point of the branch including the phase shifter in the modulator has shifted from the third target bias point and the degree of shift. This ensures the reliability and accuracy of controlling the branch including the phase shifter at the third target bias point. Furthermore, it effectively avoids crosstalk between the detection signal and the service signal, improving control precision.

[0024] Based on the first aspect, in one optional implementation, the absolute value of the third disturbance signal voltage remains unchanged during the duration of the third disturbance signal, the absolute value of the fourth disturbance signal voltage remains unchanged during the duration of the fourth disturbance signal, and the absolute value of the third disturbance signal voltage is equal to the absolute value of the fourth disturbance signal voltage.

[0025] This implementation effectively improves the accuracy and efficiency of controlling the bias point of the modulator, including the phase shifter branch, at the third target bias point.

[0026] Based on the first aspect, in one optional implementation, the absolute value of the first disturbance signal voltage is equal to the absolute value of the third disturbance signal voltage, and the absolute value of the second disturbance signal voltage is equal to the absolute value of the fourth disturbance signal voltage.

[0027] This implementation effectively improves the accuracy and efficiency of controlling the bias point of the modulator, including the phase shifter branch, at the third target bias point.

[0028] Based on the first aspect, in one optional implementation, between time intervals of two adjacent service signals output by the modulator, the bias controller sends at least one of the following to the modulator:

[0029] At least one of the third target signals, or at least one of the fourth target signals.

[0030] Using this implementation, at least one of the third target signals or at least one of the fourth target signals can be flexibly sent to the first branch of the modulator, improving the flexibility of sending disturbances to the first branch of the modulator.

[0031] Based on the first aspect, in an optional implementation, the bias control signal includes a first pair of control signals, a second pair of control signals, a third pair of control signals, and a fourth pair of control signals. The first pair of control signals includes a first target signal superimposed with a first disturbance signal of positive polarity, and includes a third target signal superimposed with a third disturbance signal of positive polarity. The second pair of control signals includes a second target signal superimposed with a second disturbance signal of negative polarity, and includes a fourth target signal superimposed with a fourth disturbance signal of positive polarity. The third pair of control signals includes a first target signal superimposed with a first disturbance signal of positive polarity, and includes a third target signal superimposed with a third disturbance signal of negative polarity. The fourth pair of control signals includes a second target signal superimposed with a second disturbance signal of negative polarity, and includes a fourth target signal superimposed with a fourth disturbance signal of negative polarity.

[0032] This implementation improves the reliability and accuracy of controlling the bias point of the modulator, including the phase shifter branch, at the third target bias point.

[0033] Based on the first aspect, in one optional implementation, the bias controller sends the target signal to the modulator during each of at least one first loading time period, wherein the amplitude of the target signal is continuously changing within the first loading time period, and the amplitude of the target signal is a sine wave or a cosine wave; or, the bias controller sends the target signal to the modulator during each of a plurality of second loading time periods, wherein there is a time interval between two adjacent second loading time periods, and the line connecting the amplitudes of the plurality of target signals is a sine wave or a cosine wave.

[0034] This implementation method can detect whether the modulator's bias point has shifted from the target bias point and the magnitude of the shift using a target signal that is sinusoidal or cosine, ensuring the reliability of the detection. Furthermore, it avoids crosstalk caused by the target signal to the service modulation while increasing the amplitude of the target signal, thereby improving the accuracy and efficiency of controlling the modulator's bias point at the target bias point.

[0035] Based on the first aspect, in an optional implementation, before the bias controller sends a bias signal to the modulator, the method further includes: the bias controller sending a plurality of first test signals to the I-channel of the modulator, the first test signals being used to obtain a first bias signal, the first bias signal being used to control the I-channel to operate at a first target bias point, and the voltage difference between two adjacent first test signals among the plurality of first test signals being greater than or equal to a first preset value; the bias controller sending a plurality of second test signals to the Q-channel of the modulator, the second test signals being used to obtain a second bias signal, the second bias signal being used to control the Q-channel to operate at a second target bias point, and the voltage difference between two adjacent second test signals among the plurality of second test signals being greater than or equal to a second preset value; the bias controller sending a plurality of third test signals to the P-channel of the modulator, the third test signals being used to obtain a third bias signal, the third bias signal being... The signal is used to control the P-path to operate at a third target bias point. The voltage difference between two adjacent third test signals among the plurality of third test signals is greater than or equal to a third preset value. The test light signal includes a first test light and a second test light. The I-path responds to the first test signal and modulates the first test light into a third test light. The Q-path responds to the second test signal and modulates the second test light into a fourth test light. The P-path combines the third test light and the fourth test light to obtain a fifth test light, and responds to the third test signal to modulate the fifth test light into a sixth test light. The photodetector performs photoelectric conversion on the sixth test light to obtain a first feedback signal and sends the first feedback signal to the processor. The processor sends a second feedback signal to the bias controller according to the first feedback signal. The second feedback signal is used to indicate the first bias signal, the second bias voltage, and the third bias signal.

[0036] Using this implementation, there is no need to send the first test signal, the second test signal, and the third test signal to the modulator through traversal. The number of the first test signal, the second test signal, and the third test signal can be selected as needed, which improves the efficiency of obtaining the first bias signal, the second bias voltage, and the third bias signal.

[0037] Secondly, embodiments of this application provide a modulator bias control method, the method comprising: the modulator receiving a bias control signal, the bias control signal including a bias signal and a target signal, the target signal being obtained by superimposing a perturbation signal on the bias signal; during a time period when the modulator outputs a service signal, the modulator receives the bias signal; and during a time period when the modulator outputs a detection signal, the modulator receives the target signal, the detection signal being used to control the bias point of the modulator at the target bias point. For an explanation of the beneficial effects of this aspect, please refer to the first aspect, which will not be elaborated further.

[0038] Based on the second aspect, in an optional implementation, the method further includes: the modulator receiving a service electrical sequence, the service electrical sequence including multiple service electrical signals, with a time interval between any two adjacent service electrical signals; after the modulator receives a bias control signal, the method further includes: the modulator modulating the optical signal into the service signal according to the bias signal and the service electrical signals; during the time period when the modulator outputs the service signal, the modulator receives the service electrical signal; and the modulator modulates the optical signal into the detection signal according to the target signal.

[0039] Based on the second aspect, in one optional implementation, there is a time interval between the time period during which the modulator outputs the service signal and the time period during which it outputs the detection signal.

[0040] Based on the second aspect, in an optional implementation, the bias signal includes a first bias signal, the bias control signal includes a first bias control signal, the target signal includes a first target signal and a second target signal, the voltage of the first target signal is not equal to the voltage of the second target signal, and the modulator receiving the bias control signal includes: the first branch of the modulator receiving the first bias control signal, the first bias control signal including the first bias signal, the first target signal and the second target signal.

[0041] Based on the second aspect, in an optional implementation, the method further includes: the second branch of the modulator receives a second bias signal, and during the time period when the modulator outputs the service signal and during the time period when the modulator outputs the detection signal, the second branch receives the second bias signal.

[0042] Based on the second aspect, in an optional implementation, the bias signal includes a second bias signal, the bias control signal includes a second bias control signal, the target signal includes a third target signal and a fourth target signal, and the modulator receives the bias control signal including:

[0043] The second branch of the modulator receives the second bias control signal, which includes the second bias signal, the third target signal, and the fourth target signal. The time period during which the first branch receives the first target signal at least partially overlaps with the time period during which the second branch receives the third target signal, and the time period during which the first branch receives the second target signal at least partially overlaps with the time period during which the second branch receives the fourth target signal.

[0044] Based on the second aspect, in one optional implementation, the bias controller sends the target signal to the modulator during each of at least one first loading time period, wherein the amplitude of the target signal is continuously varying within the first loading time period, and the amplitude of the target signal is a sine wave or a cosine wave; or, the bias controller sends the target signal to the modulator during each of a plurality of second loading time periods, wherein there is a time interval between two adjacent second loading time periods, and the line connecting the amplitudes of the plurality of target signals is a sine wave or a cosine wave.

[0045] Thirdly, this application provides a bias control method for a modulator, the method comprising: a bias controller sending a bias control signal to a modulator, the bias control signal including a bias signal and a target signal, the target signal being obtained by superimposing a disturbance signal onto the bias signal; the modulator receiving the bias control signal, wherein during a time period when the modulator outputs a service signal, the modulator receives the bias signal, and during a time period when the modulator outputs a detection signal, the modulator receives the target signal, the detection signal being used to control the bias point of the modulator at the target bias point. For an explanation of the beneficial effects of this aspect, please refer to the first aspect, which will not be elaborated further.

[0046] Fourthly, this application provides an optical device including a modulator and a bias controller, the bias controller being configured to implement the method as described in any of the first aspects above, and the modulator being configured to implement the method as described in any of the second aspects above.

[0047] Based on the fourth aspect, in an optional implementation, the optical device further includes a light source for transmitting optical signals to the modulator.

[0048] Fifthly, this application provides a processing apparatus including a module for performing any of the methods described in the first aspect. For example, the processing apparatus may be a logic module or software in a bias controller, or a component or device in a bias controller, etc.

[0049] In a sixth aspect, this application provides a chip including at least one processing device and an interface, the interface being used to implement signal transmission between the at least one processing device and an external source, the at least one processing device being used to implement the method described in any of the first aspects above.

[0050] Based on the sixth aspect, in an optional implementation, the chip further includes a modulator connected to the processing device, the modulator being used to implement the method as described in any of the second aspects above.

[0051] In a seventh aspect, this application provides a computer-readable storage medium including instructions that, when executed by a processing device, implement the method as described in any of the first aspects above.

[0052] Eighthly, this application provides a computer program product including instructions that, when executed on a processing device, perform the method described in any of the first aspects above.

[0053] Ninthly, this application provides an optical network including one or more optical devices, as shown in the fourth aspect, which will not be described in detail here. Attached Figure Description

[0054] Figure 1 is a structural example diagram of the optical device provided in this application;

[0055] Figure 2 is a flowchart of the first embodiment of the modulator bias control method provided in this application;

[0056] Figure 3 is a structural example diagram of an embodiment of the modulator provided in this application;

[0057] Figure 4 is an example diagram of the first embodiment of the control I-path bias point provided in this application;

[0058] Figure 5 is a flowchart of the steps of a second embodiment of the modulator bias control method provided in this application;

[0059] Figure 6 is an example diagram of a first embodiment of the control Q-path bias point provided in this application;

[0060] Figure 7 is a flowchart of the steps of a third embodiment of the modulator bias control method provided in this application;

[0061] Figure 8 is an example diagram of the first embodiment of the control P-path bias point provided in this application;

[0062] Figure 9 is a flowchart of the steps of the fourth embodiment of the modulator bias control method provided in this application;

[0063] Figure 10 is an example diagram of a second embodiment of the control I-path bias point provided in this application;

[0064] Figure 11 is an example diagram of a third embodiment of the control I-path bias point provided in this application;

[0065] Figure 12 is an example diagram of a fourth embodiment of the control I-path bias point provided in this application;

[0066] Figure 13 is a flowchart of the steps for obtaining the bias voltage provided in this application;

[0067] Figure 14 is a structural example diagram of an embodiment of the optical device provided in this application;

[0068] Figure 15 is a structural example diagram of an embodiment of the processing apparatus provided in this application;

[0069] Figure 16 is a structural example diagram of an embodiment of the chip provided in this application. Detailed Implementation

[0070] The present application will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present application, but do not limit the present application in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of this application.

[0071] This application provides a modulator bias control method that effectively improves the control efficiency and accuracy of controlling the modulator bias point at the target bias point while avoiding crosstalk to services. Controlling the modulator bias point refers to the process of stabilizing the modulator bias point at the target bias point through a feedback control mechanism. Specifically, the modulator bias point is defined as the operating state of the modulator when there is no service electrical signal input, determined by the bias voltage applied to the modulator. The operating state includes the amplitude, phase, or polarization characteristics of the modulator's output optical signal. By controlling the modulator bias point at the target bias point, the modulator can operate within a specific range of the transmission curve, thereby controlling the modulator's target response characteristics, such as linearity, extinction ratio, and phase error. The transmission curve refers to the relationship between the modulator's output optical power and the input bias voltage. This embodiment does not limit the type of the target bias point; for example, the target bias point can be a null point, peak point, +quad point, -quad point, etc.

[0072] First, the structure of the optical device used in the method provided in this application is described with reference to Figure 1, which is an example diagram of the structure of the optical device provided in this application. The optical device 100 shown in this example includes a light source 101, a modulator 103, a beam splitter 104, a photodetector 106, a bias controller 107, a service module 108, an analog-to-digital converter 109, a processor 120, and an optical fiber 110. The light source 101, modulator 103, beam splitter 104, and optical fiber 110 are connected sequentially. The beam splitter 104, photodetector 106, analog-to-digital converter 109, and processor 120 are also connected sequentially. The modulator 103 is connected to both the service module 108 and the bias controller 107. The service module 108 is connected to the bias controller 107. The processor 120 is also connected to the bias controller 107. This example uses the splitter 104, photodetector 106, and modulator 103 as discrete components. In other examples, the splitter 104 and photodetector 106 may also be integrated into the modulator 103; no specific limitation is made. This example does not limit the type of processor 120. For example, processor 120 may include one or more chips, or one or more integrated circuits. Furthermore, processor 120 may include one or more of the following: neural processing unit (NPU), optical digital signal processor (oDSP), field-programmable gate array (FPGA), application-specific integrated circuit (ASIC), system-on-chip (SoC), central processing unit (CPU), network processor (NP), microcontroller unit (MCU), programmable logic device (PLD), network interface card chip, storage interface chip, or other integrated chips; specific details are not elaborated further. This example demonstrates a separation of the bias controller 107 and processor 120. For a description of the type of bias controller 107, please refer to the description of processor 120; details will not be repeated here. In other examples, the bias controller 107 may also be integrated into processor 120. This example also demonstrates a separation of the service module 108 from both processor 120 and bias controller 107. The service module 108 may also be integrated into either processor 120 or bias controller 107; there are no specific limitations.

[0073] Based on the structure of the optical device shown in Figure 1, and in conjunction with Figure 2, the execution process of the modulator bias control method provided in the embodiments of this application is explained, wherein Figure 2 is a flowchart of the first embodiment of the modulator bias control method provided in this application.

[0074] Step 201: The light source sends an optical signal to the modulator.

[0075] The structure of the modulator is illustrated in Figure 3, which is an example diagram of an embodiment of the modulator provided in this application. Figure 3 shows an IQ-MZM or DP-IQ-MZM modulator as an example. This embodiment specifically includes a beam splitter 304, and in-phase (I) and quadrature (Q) path connected to the beam splitter 304, respectively. It also includes a phase shifter (P) path connected to the I and Q paths, wherein the I path includes MZM 301, the Q path includes MZM 302, and the P path includes a phase shifter 303. In this embodiment, the beam splitter 304 is connected to the light source 101. The bias controller 107 is connected to MZM 301, MZM 302, and the phase shifter 303. The service module 108 is connected to MZM 301, MZM 302, and the phase shifter 303. It should be clarified that the description of the modulator structure in this embodiment is an optional example and is not limited. For example, the modulator may include two branches, one branch being an I-path and the other a Q-path; alternatively, the modulator may only include an I-path or a Q-path; or the modulator may include multiple I-paths or Q-paths connected in parallel. This embodiment takes detecting whether the bias point of the first branch of the modulator is offset relative to the first target bias point as an example. This embodiment takes the first branch as an I-path and the second branch as a Q-path as an example, without limitation. For example, the first branch to be detected as offset from the first target bias point can be any branch included in the modulator. This embodiment takes controlling the bias point of the I-path at the first target bias point, and taking the first target bias point as null as an example. When the bias point of the I-path of the modulator is controlled at null, the I-path will operate at the lowest light intensity point of the transmission curve, thereby maximizing the extinction ratio of the optical signal output by the I-path. As shown in Figure 3, when the beam splitter 304 receives the optical signal from the light source 101, it splits the optical signal to obtain a first sub-optical signal and a second sub-optical signal. The beam splitter 304 transmits the first sub-optical signal to the I-path and the second sub-optical signal to the Q-path. This embodiment does not limit the type of the light source 101. For example, the light source 101 can be a narrow-linewidth laser, a single-frequency laser, a tunable laser, etc. This embodiment uses a narrow-linewidth laser as an example.

[0076] Step 202: The service module transmits the service electrical sequence to the modulator.

[0077] Specifically, the service module may include a digital processing unit and a digital-to-analog converter (DAC). The digital processing unit maps the service data into a complex signal and splits the complex signal into two real signals: one is an I-channel digital signal (the real part of the service data), and the other is a Q-channel digital signal (the imaginary part of the service data). The I-channel and Q-channel digital signals are two time-aligned digital signals. The DAC performs digital-to-analog conversion on the I-channel and Q-channel digital signals respectively to obtain an I-channel analog signal and a Q-channel analog signal. The I-channel analog signal includes multiple time-discrete I-channel sub-signals, with a time interval between any two adjacent I-channel sub-signals. The Q-channel analog signal includes multiple time-discrete Q-channel sub-signals, with a time interval between any two adjacent Q-channel sub-signals. For example, as shown in Figure 4, which is an example diagram of the first embodiment of controlling the I-channel bias point provided in this application. The service module transmits a service electrical sequence to the modulator, specifically including multiple service electrical signals, with a time interval between any two adjacent service electrical signals. Each service signal includes one I-channel sub-signal and one Q-channel sub-signal. A time interval between any two adjacent service signals means that there is a time interval between the I-channel sub-signals and between the Q-channel sub-signals of the two service signals. In this embodiment, the multiple I-channel sub-signals and multiple Q-channel sub-signals are synchronized. For example, during a service time period, the service module sends one I-channel sub-signal to the modulator's I-channel and also sends one Q-channel sub-signal to the modulator's Q-channel during the same service time period. The service time periods shown in Figure 4 can be time intervals from t1 to t2, t5 to t6, t9 to t10, t13 to t14, and so on. It can be understood that there is a time interval between two adjacent service time periods.

[0078] Step 203: The bias controller sends the first bias control signal to the I channel of the modulator.

[0079] The bias controller shown in this embodiment aims to control the bias point of channel I at the null point and modulate the channel I sub-signals, including the service electrical signal, into the first service optical signal. Therefore, the bias controller sends a first bias control signal to channel I. Specifically, this first bias control signal includes a first bias signal and a target signal. The target signal is obtained by superimposing a perturbation signal onto the first bias signal, and the target signal appears at intervals within the first bias control signal. It can be understood that the first bias control signal includes a first bias signal without superimposed perturbation signal, and a target signal with superimposed perturbation signal. The first bias signal without superimposed perturbation signal and the target signal with superimposed perturbation signal appear in the first bias control signal in a time-division manner.

[0080] The bias controller has pre-determined the bias voltage Va0 of channel I operating at the first target bias point (e.g., null point). To achieve modulation of each channel's sub-signals by channel I, the bias controller sends a first bias signal (without superimposed disturbance signal) to channel I during the service time period. The voltage of this first bias signal is the first bias voltage Va0, thus controlling the bias point of channel I at the null point. Optionally, the service module can send first synchronization information to the bias controller, which is used to indicate each service time period.

[0081] The target signals sent by the bias controller to the I-channel (i.e., the first bias signal superimposed with a perturbation signal) specifically include K1 first target signals and K2 second target signals, where K1 and K2 are any integers greater than or equal to 1. These first and second target signals are used to control the bias point of the I-channel near the first target bias point (e.g., the null point). Specifically, the first target signals are obtained by the bias controller superimposing the first perturbation signal onto the first bias signal, and the second target signals are obtained by the bias controller superimposing the second perturbation signal onto the first bias signal. The voltage of the first target signal is the sum of the voltage Va0 of the first bias signal and the voltage Va1 of the first perturbation signal, and the voltage of the second target signal is the sum of the voltage Va0 of the first bias signal and the voltage Va2 of the second perturbation signal. The polarity of the voltage Va1 of the first perturbation signal is opposite to the polarity of the voltage Va2 of the second perturbation signal. For example, if the voltage Va0 of the first bias signal is 3V, the voltage Va1 of the first disturbance signal is 0.2V, and the voltage Va2 of the second disturbance signal is -0.2V, then the voltage of the first target signal is 3V + 0.2V = 3.2V, and the voltage of the second target signal is 3V - 0.2V = 2.8V.

[0082] The following explains how the target signal appears intermittently in the first bias control signal.

[0083] Specifically, the bias controller sends a target signal to the I-channel during the first disturbance time period. The intersection of the first disturbance time period and the service time period is empty, and there is a time interval between the first disturbance time period and the service time period. Optionally, the bias controller shown in this embodiment can obtain each first disturbance time period based on the first synchronization signal from the service module, and there is a time interval between two adjacent first disturbance time periods. Taking Figure 4 as an example, the multiple first disturbance time periods include the time period from time t3 to time t4, the time period from time t7 to time t8, the time period from time t11 to time t12, the time period from time t15 to time t16, and so on. For example, during the first disturbance period from time t3 to time t4, the bias controller sends a first target signal (e.g., the voltage of the first target signal = 3.2V) to channel I. During the first disturbance period from time t7 to time t8, the bias controller sends a second target signal (e.g., the voltage of the second target signal = 2.8V) to channel I. During the first disturbance period from time t11 to time t12, the bias controller sends a first target signal (e.g., the voltage of the first target signal = 3.2V) to channel I. During the first disturbance period from time t15 to time t16, the bias controller sends a second target signal (e.g., the voltage of the second target signal = 2.8V) to channel I. In this embodiment, each service time period and the first disturbance time period have a time interval, thereby avoiding crosstalk caused by the first and second target signals to the process of modulating the service electrical signal onto the optical signal, effectively reducing the bit error rate.

[0084] In this embodiment, the voltages of the K1 first target signals are obtained by superimposing the voltages of the K1 first perturbation signals onto the voltage of the first bias signal (for example, K1=2 as shown in Figure 4). The voltages of the K2 second target signals are obtained by superimposing the voltages of the K2 second perturbation signals onto the first bias signal (for example, K2=2 as shown in Figure 4). Among the voltages of the K1 first perturbation signals, the voltages of any two first perturbation signals are equal (for example, both equal to 0.2V). Among the voltages of the K2 second perturbation signals, the voltages of any two second perturbation signals are equal (for example, both equal to -0.2V). During the duration of the first perturbation signal, the voltage of the first perturbation signal remains unchanged. During the duration of the second perturbation signal, the voltage of the second perturbation signal remains unchanged. Furthermore, the absolute values ​​of the voltages of the first and second perturbation signals are equal (for example, both are 0.2V). By using the voltages of K1 first perturbation signals and K2 second perturbation signals as shown in this embodiment, the accuracy of controlling the bias point of the modulator's I-path at the first target bias point can be effectively improved. It should be noted that in other examples, the voltages of any two of the K1 first perturbation signals may be unequal, exhibiting a certain deviation; or the voltages of any two of the K2 second perturbation signals may be unequal, exhibiting a certain deviation. The magnitude of this deviation is not limited. In other examples, the absolute values ​​of the first and second perturbation signal voltages may also be unequal, and a certain deviation may exist between them. The magnitude of this deviation is not limited, as long as the bias controller controls the bias point of the modulator's I-path at the first target bias point by superimposing the first and second perturbation signals onto the first bias signal.

[0085] In this embodiment, within the time interval between two adjacent service time periods, the bias controller sends at least one of the following to the I-channel:

[0086] For a description of the business time period, please refer to the above description, and we will not repeat the details here.

[0087] Continuing, for example, as shown in Figure 4, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes at least one first target signal; the time interval between the service period from time t5 to time t6 and the service period from time t9 to time t10 includes at least one second target signal, and so on, without limitation. For example, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes at least one first target signal and at least one second target signal; for example, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes at least one second target signal, and so on.

[0088] Step 204: The I-path of the modulator modulates the first sub-optical signal into the first service optical signal.

[0089] The I-path operating at the null point can modulate the received I-path sub-signal onto the first sub-optical signal to obtain the first service optical signal. Continuing with Figure 4, the I-path modulates the received I-path sub-signal during the service time period from time t1 to time t2 onto the first sub-optical signal to obtain the first service optical signal c1; the I-path modulates the received I-path sub-signal during the service time period from time t5 to time t6 onto the first sub-optical signal to obtain the first service optical signal c2; the I-path modulates the received I-path sub-signal during the service time period from time t9 to time t10 onto the first sub-optical signal to obtain the first service optical signal c3; and the I-path modulates the received I-path sub-signal during the service time period from time t9 to time t10 onto the first sub-optical signal to obtain the first service optical signal c4.

[0090] Step 205: The I-channel of the modulator modulates the first sub-optical signal into a detection light according to the target signal.

[0091] Specifically, when the modulator's I-channel receives K1 first target signals from the bias controller, the I-channel modulates a first sub-optical signal according to the K1 first target signals to obtain a first detection light. When the modulator's I-channel receives K2 second target signals from the bias controller, the I-channel modulates the first sub-optical signal according to the K2 second target signals to obtain a second detection light. It can be understood that the detection light output from the I-channel shown in this embodiment includes both the first and second detection lights.

[0092] Step 206: The bias controller sends a second bias signal to the Q path of the modulator.

[0093] This embodiment takes the requirement for the Q-path to operate at a second target bias point as an example. For instance, if the second target bias point is null, the bias controller has already obtained the bias voltage Vb0 for the Q-path to operate at the null point. To achieve the modulation of each Q-path sub-signal by the Q-path and to control the bias point of the I-path at the null point, the bias controller continuously sends a second bias signal to the Q-path (e.g., from time t1 to time t16) to control the bias point of the Q-path at the null point. For an explanation of how the bias controller sends the second bias signal to the Q-path, please refer to the explanation of how the bias controller sends the first bias signal to the I-path in step 203; details will not be repeated here.

[0094] Step 207: The Q path of the modulator modulates the second sub-optical signal into the second service optical signal.

[0095] The Q-path operating at the null point can modulate the received Q-path sub-signals onto the second sub-optical signal to obtain the second service optical signal. Continuing with Figure 4, the Q-path modulates the received Q-path sub-signals received during the service period from time t1 to time t2 onto the second sub-optical signal to obtain the second service optical signal d1; the Q-path modulates the received Q-path sub-signals received during the service period from time t5 to time t6 onto the second sub-optical signal to obtain the second service optical signal d2; the Q-path modulates the received Q-path sub-signals received during the service period from time t9 to time t10 onto the second sub-optical signal to obtain the second service optical signal d3; and the Q-path modulates the received Q-path sub-signals received during the service period from time t9 to time t10 onto the second sub-optical signal to obtain the second service optical signal d4.

[0096] Step 208: The Q path of the modulator modulates the second sub-optical signal into the third detection light.

[0097] Specifically, the bias controller sends a second bias signal to the Q-path during the second disturbance period, which coincides with the first disturbance period. The Q-path of the bias controller operates at the second target bias point based on the second bias signal and modulates the second sub-optical signal into the third detection light. As shown in steps 207 and 208, the modulator's Q-path outputs the second service light and the third detection light in a time-division multiplexing manner. It can be understood that during the time period t3 to t4, the bias controller sends a first target signal to the I-path and a second bias signal to the Q-path; therefore, during the time period t3 to t4, the Q-path modulates the second sub-optical signal into the third detection light. Similarly, during the time period t7 to t8, the bias controller sends a second target signal to the I-path and a second bias signal to the Q-path; therefore, during the time period t7 to t8, the Q-path modulates the second sub-optical signal into the third detection light. During the time interval t11 to t12, the bias controller sends a first target signal to channel I and a second bias signal to channel Q. Therefore, during the time interval t11 to t12, channel Q modulates the second sub-optical signal into the third detection light. During the time interval t15 to t16, the bias controller sends a second target signal to channel I and a second bias signal to channel Q. Therefore, during the time interval t15 to t16, channel Q modulates the second sub-optical signal into the third detection light. It can be understood that, during the time period when the bias controller shown in this embodiment sends the first target signal and the second target signal to the I channel, it sends the second bias signal to the Q channel. That is, only the first target signal and the second target signal sent to the I channel are subjected to a small-amplitude perturbation (i.e., the voltage of the first perturbation signal and the voltage of the second perturbation signal). This avoids crosstalk to controlling the bias point of the I channel to the first target bias point due to the small-amplitude perturbation sent to the Q channel, and effectively improves the accuracy and efficiency of controlling the bias point of the I channel to the first target bias point.

[0098] Step 209: The bias controller sends a third bias signal to the P-path of the modulator.

[0099] This embodiment takes the requirement for the P-path to operate at a third target bias point as an example. For instance, this third target bias point is the +quad point. The bias controller has already obtained the bias voltage for the P-path to operate at the +quad point as the third bias signal. To achieve modulation of the P-path, the bias controller sends the third bias signal to the P-path to control its bias point at the +quad point. When the bias point of the modulator's P-path is controlled at the +quad point, the P-path will operate at the midpoint of the positive slope linear region of the transmission curve.

[0100] Step 210: The P-path of the modulator modulates the optical signal from the I-path and the optical signal from the Q-path to obtain the modulated optical signal.

[0101] The optical signal transmitted from channel I to channel P includes a first service light (see step 204) and a detection light (see the first and second detection lights in step 205). The optical signal transmitted from channel Q to channel P includes a second service light (see step 207) and a third detection light (see step 208). Channel P, operating at the +quad point, combines the optical signals from channel I and channel Q and performs phase modulation to obtain a modulated optical signal, thereby improving channel capacity.

[0102] The modulator shown in this embodiment outputs a modulated optical signal via the P-path. Specifically, the modulated optical signal includes a service signal and a detection signal. Both the service signal and the detection signal are optical signals. The service signal includes multiple sub-service signals, and the detection signal includes multiple sub-detection signals. More specifically, within the same service time period, the first service light output from the I-path and the second service light output from the Q-path are combined and phase-modulated by the P-path to obtain the corresponding sub-service signal. For example, as shown in Figure 4, the I-path and Q-path send the first service light and the second service light to the P-path within the same service time period (e.g., time t1 to time t2). After the P-path performs beam combining and phase modulation, the sub-service signal 401 is obtained. It can be understood that the first bias signal and the second bias signal at the modulator loading time (e.g., time t1 to time t2) correspond to the time (e.g., time t1 to time t2) when the modulator outputs the service signal (specifically the sub-service signal 401). That is, during the time period when the modulator outputs the sub-service signal 401 (e.g., from time t1 to time t2), the modulator receives a bias signal (i.e., the I-channel receives a first bias signal from time t1 to time t2, and the Q-channel receives a second bias signal from time t1 to time t2). The I-channel and Q-channel send the first service light and the second service light to the P-channel during the same service time period (e.g., from time t5 to time t6). After beam combining and phase modulation, the P-channel obtains the sub-service signal 402. It can be understood that the first bias signal and the second bias signal during the modulator's loading time (e.g., from time t5 to time t6) correspond to the time when the modulator outputs the service signal (specifically the sub-service signal 402) (e.g., from time t5 to time t6). That is, during the time period when the modulator outputs sub-service signal 402 (e.g., from time t5 to time t6), the modulator receives a bias signal (i.e., the I-channel receives a first bias signal from time t5 to time t6, and the Q-channel receives a second bias signal from time t5 to time t6). The I-channel and Q-channel send the first service light and the second service light to the P-channel during the same service time period (e.g., from time t9 to time t10). After beam combining and phase modulation, the P-channel obtains sub-service signal 403. It can be understood that the first bias signal and the second bias signal during the modulator's loading time (e.g., from time t9 to time t10) correspond to the time when the modulator outputs the service signal (specifically, sub-service signal 403) (e.g., from time t9 to time t10). That is, during the time period when the modulator outputs the sub-service signal 403 (e.g., from time t9 to time t10), the modulator receives a bias signal (i.e., the I channel receives a first bias signal from time t9 to time t10, and the Q channel receives a second bias signal from time t9 to time t10).During the same service time period (e.g., from time t13 to time t14), both I and Q paths transmit the first and second service optical signals via P path. After beam combining and phase modulation, sub-service signal 404 is obtained. It can be understood that the first and second bias signals at the modulator loading time (e.g., from time t13 to time t14) correspond to the time when the modulator outputs the service signal (specifically, sub-service signal 404) (e.g., from time t13 to time t14). That is, during the time period when the modulator outputs sub-service signal 404 (e.g., from time t13 to time t14), the modulator receives the bias signal (i.e., I path receives the first bias signal from time t13 to time t14, and Q path receives the second bias signal from time t13 to time t14).

[0103] During the same time period, the first detection light output from the I-channel and the third detection light output from the Q-channel are combined and phase-modulated by the P-channel to obtain corresponding sub-detection signals. Similarly, during the same time period, the second detection light output from the I-channel and the third detection light output from the Q-channel are combined and phase-modulated by the P-channel to obtain corresponding sub-detection signals. For example, during the same time period (e.g., from time t3 to time t4), the first detection light output from the I-channel and the third detection light output from the Q-channel are combined and phase-modulated by the P-channel to obtain sub-detection signal 411. It can be understood that the loading time of the first target signal in the modulator (e.g., from time t3 to time t4) corresponds to the time when the modulator outputs the detection signal (specifically, sub-detection signal 411) (e.g., from time t3 to time t4). That is, during the time period when the modulator outputs sub-detection signal 411 (e.g., from time t3 to time t4), the I-channel receives the first target signal from time t3 to time t4, and the Q-channel receives the second bias signal from time t3 to time t4. During the same time period (e.g., from time t7 to time t8), the second detection light output from the I-channel and the third detection light output from the Q-channel are combined and phase-modulated by the P-channel to obtain the sub-detection signal 412. It can be understood that the loading time of the first target signal in the modulator (e.g., from time t7 to time t8) corresponds to the time when the modulator outputs the detection signal (specifically, the sub-detection signal 412) (e.g., from time t7 to time t8). That is, during the time period when the modulator outputs the sub-detection signal 412 (e.g., from time t7 to time t8), the I-channel receives the second target signal from time t7 to time t8, and the Q-channel receives the second bias signal from time t7 to time t8. During the same time period (e.g., from time t11 to time t12), the first detection light output from the I-channel and the third detection light output from the Q-channel are combined and phase-modulated by the P-channel to obtain the sub-detection signal 413. It can be understood that the loading time of the first target signal in the modulator (e.g., from time t11 to time t12) corresponds to the time when the modulator outputs the detection signal (specifically the sub-detection signal 413) (e.g., from time t11 to time t12). That is, during the time period when the modulator outputs the sub-detection signal 413 (e.g., from time t11 to time t12), the I-channel receives the first target signal from time t11 to time t12, and the Q-channel receives the second bias signal from time t11 to time t12. During the same time period (e.g., from time t15 to time t16), the second detection light output from the I-path and the third detection light output from the Q-path are combined by the P-path and phase modulated to obtain the sub-detection signal 414. It can be understood that the loading time of the first target signal in the modulator (e.g., from time t15 to time t16) corresponds to the time when the modulator outputs the detection signal (specifically the sub-detection signal 414) (e.g., from time t15 to time t16).That is, during the time period of the modulator output sub-detection signal 414 (e.g., from time t15 to time t16), the I channel receives the second target signal from time t15 to time t16, and the Q channel receives the second bias signal from time t15 to time t16.

[0104] In this embodiment, the modulated optical signal corresponds to one of the sub-service signal and the sub-detection signal at the same time. It can be understood that the sub-service signal and the sub-detection signal appear in the modulated optical signal in a time-division multiplexing manner. For example, the modulated optical signal corresponds to sub-service signal 401 during the time period from time t1 to time t2, and to sub-detection signal 411 during the time period from time t3 to time t4. The modulated optical signal shown in this embodiment also includes idle light, which refers to an optical signal that has not been modulated by the modulator of the service electrical sequence and has not been modulated by the modulator of the perturbation signal. It can be understood that during the time period when the modulator outputs idle light, the modulator receives a bias signal (i.e., no superimposed perturbation signal). For example, in the modulated optical signal, the idle light is located between adjacent sub-service signals and sub-detection signals; or, for example, the idle light is located between two adjacent sub-service signals; or, for example, the idle light is located between two adjacent sub-detection signals. Referring to the example shown in Figure 4, the optical signal corresponding to the modulated optical signal from time t2 to time t3 is idle light 421. It can be understood that the idle light 421 is located between the sub-service signal 401 and the sub-detection signal 411 in the modulated optical signal.

[0105] Step 211: The modulator sends the modulated optical signal to the splitter.

[0106] Step 212: After the optical signal is split and modulated by the beam splitter, a first beam split signal and a second beam split signal are obtained. The first beam split signal is sent to the processor, and the second beam split signal is output.

[0107] In this embodiment, the splitting ratio of the optical signal from the modulator to the optical signal from the beam splitter is not limited. For example, the beam splitter uses 10% of the modulated optical signal as the first splitting signal and 90% of the modulated optical signal as the second splitting signal. The beam splitter outputs the second splitting signal, which is then used as the output of the modulator.

[0108] Referring to Figure 1, the beam splitter sends a first beam-splitting signal to the photodetector. Optionally, an optical amplifier can be connected between the beam splitter and the photodetector. The optical amplifier amplifies the optical power of the first beam-splitting signal to obtain an amplified first beam-splitting signal, and sends the amplified first beam-splitting signal to the photodetector. The photodetector performs photoelectric conversion on the first beam-splitting signal to obtain a detection electrical signal. The photodetector sends the detection electrical signal to an analog-to-digital converter (ADC). The ADC performs analog-to-digital conversion on the detection electrical signal to obtain a digital signal, and the ADC sends the digital signal to a processor.

[0109] Step 213: The processor sends the first bias adjustment command to the bias controller.

[0110] The processor performs a Fast Fourier Transform (FFT) on the digital signal to extract the first harmonic amplitude S1 and the second harmonic amplitude S2. The processor obtains the target ratio R = S1 / S2. To control the bias point of the I-channel at null, the amplitude of the first harmonic needs to be extremely small, and the amplitude of the second harmonic needs to be extremely large. Therefore, to control the bias point of the I-channel at null, the target ratio R needs to approach zero. The processor obtains an error signal e, which is R target - R, where R target = 0. Based on the error signal e, the processor obtains the bias voltage adjustment amount ΔV. The processor sends a first bias adjustment command to the bias controller, indicating the bias voltage adjustment amount ΔV. The bias controller adjusts the magnitude of the first bias signal voltage according to the first bias adjustment command and sends the adjusted first bias signal to the I-channel until the bias point of the I-channel is precisely controlled at null.

[0111] Optionally, the optical device shown in this embodiment may further include an amplitude modulator connected to the modulator. The amplitude modulator receives the second split signal from the beam splitter and controls the amplitude of the idle light in the second split signal to be close to zero or low enough not to affect system performance, thereby improving the extinction ratio, avoiding signal degradation, and reducing crosstalk. In this embodiment, the service module may send a second synchronization signal to the amplitude modulator. This second synchronization signal indicates the time period occupied by the idle light. The amplitude modulator can then suppress or eliminate the amplitude of the idle light in the received second split signal according to the second synchronization signal. The optical device outputs the second split signal modulated by the amplitude modulator. Alternatively, if the idle light in the modulated optical signal output by the modulator shown in this embodiment has been eliminated or suppressed by the modulator, the optical device may not include the amplitude modulator. In this case, the optical device directly outputs the second split signal after beam splitting by the beam splitter. Alternatively, the optical device may not suppress or eliminate the idle light in the modulated optical signal; this is not specifically limited.

[0112] As shown in this embodiment, the service module sends a service electrical signal to the modulator during the service time period. The bias controller sends a first target signal and a second target signal to the modulator during the first disturbance time period. Since there is a time interval between the service time period and the first disturbance time period, it ensures that the modulated optical signal output by the modulator corresponds to either the service signal or the detection signal at the same time. It can be understood that in the modulated optical signal, the service signal corresponding to the bias signal and the detection signal corresponding to the target signal appear in a time-division manner, effectively avoiding crosstalk between the detection signal and the service signal. Because there is a time interval between the service time period and the first disturbance time period, the mixing of the service electrical signal sent to the modulator with the first and second target signals is effectively avoided. This prevents crosstalk between the first and second target signals and the service modulation, while also increasing the amplitude of the voltage of the disturbance signal used to obtain the first and second target signals (i.e., the voltage of the first and second disturbance signals as shown above), thereby improving the accuracy and efficiency of controlling the bias point of the I-channel at the first target bias point.

[0113] The embodiment shown in Figure 2 illustrates the process of controlling the bias point of the first branch (i.e., I-path) of the modulator to the first target bias point (e.g., null point). Figure 5 illustrates the process of controlling the bias point of the second branch (i.e., Q-path) of the modulator to the second target bias point (e.g., null point). Figure 5 is a flowchart of the steps of the second embodiment of the modulator bias control method provided in this application.

[0114] Step 501: The light source sends an optical signal to the modulator.

[0115] Step 502: The service module transmits the service electrical sequence to the modulator.

[0116] For an explanation of the execution process of steps 501 to 502 shown in this embodiment, please refer to steps 201 to 202 in Figure 2. Detailed explanations will not be repeated here.

[0117] Step 503: The bias controller sends a second bias control signal to the Q path of the modulator.

[0118] The bias controller shown in this embodiment aims to control the bias point of the Q-path at the null point and enable the Q-path to modulate the Q-path sub-signals, including the service electrical signal, into the second service optical signal. Therefore, the bias controller sends a second bias control signal to the Q-path. Specifically, this second bias control signal includes a second bias signal and a target signal. The target signal is obtained by the bias controller superimposing a perturbation signal onto the second bias signal, and the target signal appears intermittently within the second bias control signal. It can be understood that the second bias control signal includes a second bias signal without superimposed perturbation signal, and a target signal with superimposed perturbation signal, and the second bias signal without superimposed perturbation signal and the target signal with superimposed perturbation signal appear in the second bias control signal in a time-division manner.

[0119] The bias controller has pre-determined the bias voltage Vb0 for the Q-path to operate at the second target bias point (e.g., the null point). To achieve modulation of each Q-path sub-signal by the Q-path, the bias controller sends a second bias signal (without superimposed disturbance signal) to the Q-path during the service period. The voltage of this second bias signal is the second bias voltage Vb0, thus controlling the bias point of the Q-path at the null point. Optionally, the service module can send second synchronization information to the bias controller, which is used to indicate each service time period.

[0120] The target signals sent by the bias controller to the Q-channel (i.e., the second bias signal superimposed with a perturbation signal) specifically include K3 first target signals and K4 second target signals. K3 and K4 are any integers greater than or equal to 1. These first and second target signals are used to control the bias point of the I-channel near the first target bias point (e.g., the null point). Specifically, the first target signals are obtained by the bias controller superimposing the first perturbation signal onto the second bias signal, and the second target signals are obtained by the bias controller superimposing the second perturbation signal onto the second bias signal. Specifically, the voltage of the first target signal is the sum of the voltage Vb0 of the second bias signal and the voltage Vb1 of the first perturbation signal; the voltage of the second target signal is the sum of the voltage Vb0 of the second bias signal and the voltage Vb2 of the second perturbation signal; and the polarity of the voltage Vb1 of the first perturbation signal is opposite to the polarity of the voltage Vb2 of the second perturbation signal. For example, if the voltage Vb0 of the second bias signal is 3V, the voltage Vb1 of the first disturbance signal is 0.2V, and the voltage Vb2 of the second disturbance signal is -0.2V, then the voltage of the first target signal is 3V + 0.2V = 3.2V, and the voltage of the second target signal is 3V - 0.2V = 2.8V.

[0121] The following explains how the target signal appears intermittently in the second bias control signal.

[0122] Specifically, the bias controller sends a target signal to the Q-channel during the first disturbance time period. The intersection of the first disturbance time period and the service time period is empty, and there is a time interval between the first disturbance time period and the service time period. Optionally, the bias controller shown in this embodiment can obtain each first disturbance time period based on the third synchronization signal from the service module, and there is a time interval between two adjacent first disturbance time periods. Taking Figure 6 as an example, the multiple first disturbance time periods include the time period from time t3 to time t4, the time period from time t7 to time t8, the time period from time t11 to time t12, the time period from time t15 to time t16, and so on. For a description of the service time period and the first disturbance time period, please refer to the description corresponding to Figure 4, which will not be repeated here. For example, during the first disturbance period from time t3 to time t4, the bias controller sends a first target signal (e.g., the voltage of the first target signal = 3.2V) to the Q-path. During the first disturbance period from time t7 to time t8, the bias controller sends a second target signal (e.g., the voltage of the second target signal = 2.8V) to the Q-path. During the first disturbance period from time t11 to time t12, the bias controller sends a first target signal (e.g., the voltage of the first target signal = 3.2V) to the Q-path. During the first disturbance period from time t15 to time t16, the bias controller sends a second target signal (e.g., the voltage of the second target signal = 2.8V) to the Q-path. In this embodiment, each service time period and the first disturbance time period have a time interval, thereby avoiding crosstalk caused by the first and second target signals to the process of modulating the service electrical signal onto the optical signal, effectively reducing the bit error rate.

[0123] The voltages of the K3 first target signals shown in this embodiment are obtained by superimposing the voltages of the K3 first disturbance signals onto the voltage of the second bias signal (for example, K3=2 as shown in Figure 6). The voltages of the K4 second target signals are obtained by superimposing the voltages of the K4 second disturbance signals onto the second bias signal (for example, K2=2 as shown in Figure 6). For a detailed explanation of the superposition, please refer to the explanation of superimposing the first disturbance signal and the second disturbance signal onto the first bias signal corresponding to Figure 2. The details will not be repeated here.

[0124] In this embodiment, within the time interval between two adjacent service time periods, the bias controller sends at least one of the following to the Q-path:

[0125] For a description of the business time period, please refer to the above description, and we will not repeat the details here.

[0126] Continuing, for example, as shown in Figure 6, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes at least one first target signal; the time interval between the service period from time t5 to time t6 and the service period from time t9 to time t10 includes at least one second target signal, and so on, without limitation. For example, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes at least one first target signal and at least one second target signal; for example, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes at least one second target signal, and so on.

[0127] Step 504: The Q path of the modulator modulates the second sub-optical signal into the second service optical signal.

[0128] The Q-path operating at the null point can modulate the received Q-path sub-signals onto the second sub-optical signal to obtain the second service optical signal. Continuing with Figure 6, the Q-path modulates the received Q-path sub-signals received during the service period from time t1 to time t2 onto the second sub-optical signal to obtain the second service optical signal e1; the Q-path modulates the received Q-path sub-signals received during the service period from time t5 to time t6 onto the second sub-optical signal to obtain the second service optical signal e2; the Q-path modulates the received Q-path sub-signals received during the service period from time t9 to time t10 onto the second sub-optical signal to obtain the second service optical signal e3; and the Q-path modulates the received Q-path sub-signals received during the service period from time t9 to time t10 onto the second sub-optical signal to obtain the second service optical signal e4.

[0129] Step 505: The Q path of the modulator modulates the second sub-optical signal into a detection light according to the target signal.

[0130] Specifically, when the modulator's Q-path receives a first target signal from the bias controller, the I-path modulates a second sub-optical signal according to the first target signal to obtain a first detection light. When the modulator's Q-path receives a second target signal from the bias controller, the Q-path modulates a second sub-optical signal according to the second target signal to obtain a second detection light. It can be understood that the detection light output by the Q-path in this embodiment includes both a first detection light and a second detection light. For a description of the first and second detection lights output by the Q-path, please refer to the description of the first and second detection lights output by the I-path in step 205 of Figure 2; further details will not be elaborated here.

[0131] Step 506: The bias controller sends the first bias signal to the I channel of the modulator.

[0132] This embodiment takes the requirement for I-channel to operate at the first target bias point as an example. For instance, the first target bias point is null. The bias controller has obtained the bias voltage Va0 for I-channel to operate at the null point in advance. In order to achieve the modulation of each I-channel sub-signal by I-channel and to achieve the purpose of controlling the bias point of Q-channel at the null point, the bias controller continuously sends the first bias signal to I-channel (for example, from time t1 to time t16) to control the bias point of I-channel at the null point.

[0133] Step 507: The I-path of the modulator modulates the first sub-optical signal into the first service optical signal.

[0134] The I-path operating at the null point can modulate the received I-path sub-signal onto the first sub-optical signal to obtain the first service optical light. Continuing with Figure 6, the I-path modulates the I-path sub-signal received during the service time period from time t1 to time t2 onto the first sub-optical signal to obtain the first service optical light d1; the I-path modulates the I-path sub-signal received during the service time period from time t5 to time t6 onto the first sub-optical signal to obtain the first service optical light d2; the I-path modulates the I-path sub-signal received during the service time period from time t9 to time t10 onto the first sub-optical signal to obtain the first service optical light d3; and the I-path modulates the I-path sub-signal received during the service time period from time t9 to time t10 onto the first sub-optical signal to obtain the first service optical light d4.

[0135] Step 508: The I-path of the modulator modulates the first sub-optical signal into the third detection light.

[0136] The bias controller's I-channel operates at the first target bias point based on the first bias signal and modulates the first sub-optical signal into the third detection light. As shown in steps 507 and 508, the modulator's I-channel outputs the first service light and the third detection light in a time-division multiplexing manner. It can be understood that during the time interval t3 to t4, the bias controller sends the first target signal to the Q-channel and the first bias signal to the I-channel; therefore, during the time interval t3 to t4, the I-channel modulates the first sub-optical signal into the third detection light. During the time interval t7 to t8, the bias controller sends the second target signal to the Q-channel and the first bias signal to the I-channel; therefore, during the time interval t7 to t8, the I-channel modulates the first sub-optical signal into the third detection light. During the time interval t11 to t12, the bias controller sends the first target signal to the Q-channel and the first bias signal to the I-channel; therefore, during the time interval t11 to t12, the I-channel modulates the first sub-optical signal into the third detection light. During the time interval from time t15 to time t16, the bias controller sends a second target signal to the Q-path and a first bias signal to the I-path. During the same time interval, the I-path modulates the first sub-optical signal into a third detection light. It can be understood that in this embodiment, the bias controller sends the first bias signal to the I-path during the time intervals when sending the first and second target signals to the Q-path. That is, only the first and second target signals sent to the Q-path are subjected to a small-amplitude perturbation (i.e., the voltage of the first perturbation signal and the voltage of the second perturbation signal). This avoids crosstalk to controlling the bias point of the Q-path to the second target bias point due to the small-amplitude perturbation sent to the I-path, effectively improving the accuracy and efficiency of controlling the bias point of the Q-path to the second target bias point.

[0137] Step 509: The bias controller sends a third bias signal to the P-path of the modulator.

[0138] Please refer to step 209 in Figure 2 for step 509 in this embodiment; the specific details will not be elaborated upon.

[0139] Step 510: The P-path of the modulator modulates the optical signal from the I-path and the optical signal from the Q-path to obtain the modulated optical signal.

[0140] The optical signals transmitted from I-channel to P-channel include a first service optical signal (see step 507) and a third detection optical signal (see step 508). The optical signals transmitted from Q-channel to P-channel include a second service optical signal (see step 504) and a detection optical signal (see the first and second detection optical signals in step 505). P-channel, operating at the +quad point, combines the optical signals from I-channel and Q-channel and performs phase modulation to obtain a modulated optical signal, thereby improving channel capacity. For an explanation of P-channel combining and modulation, please refer to step 210 in Figure 2; further details are omitted here.

[0141] For example, as shown in Figure 6, the modulator in this embodiment outputs a modulated optical signal via the P-path. Specifically, the modulated optical signal includes a service signal and a detection signal. Both the service signal and the detection signal are optical signals. The service signal includes multiple sub-service signals, and the detection signal includes multiple sub-detection signals. More specifically, within the same service time period, the first service light output from the I-path and the second service light output from the Q-path are combined and phase-modulated by the P-path to obtain the corresponding sub-service signal. For example, as shown in Figure 6, the I-path and Q-path send the first service light and the second service light to the P-path within the same service time period (e.g., time t1 to time t2). After the P-path performs combination and phase modulation, the sub-service signal 601 is obtained. It can be understood that the first bias signal and the second bias signal at the modulator loading time (e.g., time t1 to time t2) correspond to the time (e.g., time t1 to time t2) when the modulator outputs the service signal (specifically, the sub-service signal 601). That is, during the time period when the modulator outputs the sub-service signal 601 (e.g., from time t1 to time t2), the modulator receives a bias signal (i.e., the I-channel receives a first bias signal from time t1 to time t2, and the Q-channel receives a second bias signal from time t1 to time t2). The I-channel and Q-channel transmit the first service light and the second service light to the P-channel during the same service time period (e.g., from time t5 to time t6). After beam combining and phase modulation, the P-channel obtains the sub-service signal 602. It can be understood that the first bias signal and the second bias signal during the modulator's loading time (e.g., from time t5 to time t6) correspond to the time when the modulator outputs the service signal (specifically the sub-service signal 602) (e.g., from time t5 to time t6). That is, during the time period when the modulator outputs sub-service signal 602 (e.g., from time t5 to time t6), the modulator receives a bias signal (i.e., the I-channel receives a first bias signal from time t5 to time t6, and the Q-channel receives a second bias signal from time t5 to time t6). The I-channel and Q-channel send the first service light and the second service light to the P-channel during the same service time period (e.g., from time t9 to time t10). After beam combining and phase modulation, the P-channel obtains sub-service signal 603. It can be understood that the first bias signal and the second bias signal during the modulator's loading time (e.g., from time t9 to time t10) correspond to the time when the modulator outputs the service signal (specifically, sub-service signal 603) (e.g., from time t9 to time t10). That is, during the time period when the modulator outputs sub-service signal 603 (e.g., from time t9 to time t10), the modulator receives a bias signal (i.e., the I channel receives a first bias signal from time t9 to time t10, and the Q channel receives a second bias signal from time t9 to time t10).During the same service time period (e.g., from time t13 to time t14), both I-path and Q-path transmit the first and second service optical signals via P-path. After beam combining and phase modulation, sub-service signal 604 is obtained. It can be understood that the first and second bias signals at the modulator loading time (e.g., from time t13 to time t14) correspond to the time when the modulator outputs the service signal (specifically, sub-service signal 604) (e.g., from time t13 to time t14). That is, during the time period when the modulator outputs sub-service signal 604 (e.g., from time t13 to time t14), the modulator receives the bias signal (i.e., I-path receives the first bias signal from time t13 to time t14, and Q-path receives the second bias signal from time t13 to time t14).

[0142] During the same time period, the first detection light output from the Q-channel and the third detection light output from the I-channel are combined and phase-modulated by the P-channel to obtain corresponding sub-detection signals. Similarly, during the same time period, the second detection light output from the Q-channel and the third detection light output from the I-channel are combined and phase-modulated by the P-channel to obtain corresponding sub-detection signals. For example, during the same time period (e.g., from time t3 to time t4), the first detection light output from the Q-channel and the third detection light output from the I-channel are combined and phase-modulated by the P-channel to obtain sub-detection signal 611. It can be understood that the loading time of the first target signal in the modulator (e.g., from time t3 to time t4) corresponds to the time when the modulator outputs the detection signal (specifically, sub-detection signal 611) (e.g., from time t3 to time t4). That is, during the time period when the modulator outputs sub-detection signal 611 (e.g., from time t3 to time t4), the Q-channel receives the first target signal from time t3 to time t4, and the I-channel receives the first bias signal from time t3 to time t4. During the same time period (e.g., from time t7 to time t8), the second detection light output from the Q-path and the third detection light output from the I-path are combined and phase-modulated by the P-path to obtain the sub-detection signal 612. It can be understood that the loading time of the first target signal in the modulator (e.g., from time t7 to time t8) corresponds to the time when the modulator outputs the detection signal (specifically the sub-detection signal 612) (e.g., from time t7 to time t8). That is, during the time period when the modulator outputs the sub-detection signal 612 (e.g., from time t7 to time t8), the Q-path receives the second target signal from time t7 to time t8, and the I-path receives the first bias signal from time t7 to time t8. During the same time period (e.g., from time t11 to time t12), the first detection light output from the Q-path and the third detection light output from the I-path are combined and phase-modulated by the P-path to obtain the sub-detection signal 613. It can be understood that the loading time of the first target signal in the modulator (e.g., time t11 to time t12) corresponds to the time when the modulator outputs the detection signal (specifically, the sub-detection signal 613) (e.g., time t11 to time t12). That is, during the time period when the modulator outputs the sub-detection signal 613 (e.g., time t11 to time t12), the Q-channel receives the first target signal, and the I-channel receives the first bias signal. In the same time period (e.g., time t15 to time t16), the second detection light output from the Q-channel and the third detection light output from the I-channel are combined and phase-modulated by the P-channel to obtain the sub-detection signal 614. It can be understood that the loading time of the first target signal in the modulator (e.g., time t15 to time t16) corresponds to the time when the modulator outputs the detection signal (specifically, the sub-detection signal 614) (e.g., time t15 to time t16).That is, during the time period of the modulator output sub-detection signal 614 (e.g., from time t15 to time t16), the Q channel receives the second target signal from time t15 to time t16, and the I channel receives the first bias signal from time t15 to time t16.

[0143] In this embodiment, the modulated optical signal corresponds to one of the sub-service signal and the sub-detection signal at the same time. It can be understood that the sub-service signal and the sub-detection signal appear in a time-division multiplexing manner within the modulated optical signal. For example, the modulated optical signal corresponds to sub-service signal 601 during the time period from time t1 to time t2, and to sub-detection signal 611 during the time period from time t3 to time t4. The modulated optical signal shown in this embodiment also includes idle light. For an explanation of the idle light, please refer to step 210 in Figure 2; further details are omitted here.

[0144] Step 511: The modulator sends the modulated optical signal to the beam splitter.

[0145] Step 512: After the optical signal is split and modulated by the beam splitter, a first beam split signal and a second beam split signal are obtained. The first beam split signal is sent to the processor, and the second beam split signal is output.

[0146] For an explanation of the execution process of steps 511 to 512 shown in this embodiment, please refer to steps 211 to 212 in Figure 2. Detailed explanations will not be repeated here.

[0147] Step 513: The processor sends a second bias adjustment command to the bias controller.

[0148] The processor performs an FFT on the digital signal to extract the first harmonic amplitude S1 and the second harmonic amplitude S2. The processor obtains the target ratio R = S1 / S2. To control the bias point of the Q-path at null, the amplitude of the first harmonic needs to be extremely small, and the amplitude of the second harmonic needs to be extremely large. Therefore, to control the bias point of the Q-path at null, the target ratio R needs to approach zero. The processor obtains an error signal e, which is R target - R, where R target = 0. Based on the error signal e, the processor obtains the bias voltage adjustment amount ΔV. The processor sends a second bias adjustment command to the bias controller, indicating the bias voltage adjustment amount ΔV. The bias controller adjusts the magnitude of the second bias signal voltage according to the second bias adjustment command and sends the adjusted second bias signal to the Q-path until the Q-path is precisely controlled at the null point.

[0149] As shown in this embodiment, the service module sends a service electrical signal to the modulator during the service time period. The bias controller sends a first target signal and a second target signal to the modulator during the first disturbance time period. Since there is a time interval between the service time period and the first disturbance time period, it ensures that the modulated optical signal output by the modulator corresponds to either the service signal or the detection signal at the same time. This means that the service signal and the detection signal appear in the modulated optical signal in a time-division manner, effectively avoiding crosstalk between the detection signal and the service signal. Because there is a time interval between the service time period and the first disturbance time period, the mixing of the service electrical signal sent to the modulator with the first and second target signals is effectively avoided. This prevents the first and second target signals from causing crosstalk to the service modulation, and at the same time, it increases the amplitude of the voltage of the disturbance signal used to obtain the first and second target signals (i.e., the voltage of the first and second disturbance signals as shown above), thereby improving the accuracy and efficiency of controlling the bias point of the Q-path at the second target bias point.

[0150] The embodiment shown in Figure 2 illustrates the process of controlling the bias point of the I-path of the modulator at the first target bias point (e.g., null point). The embodiment shown in Figure 5 illustrates the process of controlling the bias point of the Q-path of the modulator at the second target bias point (e.g., null point). Figure 7 illustrates the process of controlling the bias point of the P-path of the modulator at the third target bias point (e.g., +quad point). Figure 7 is a flowchart of the third embodiment of the modulator bias control method provided in this application.

[0151] Step 701: The light source sends an optical signal to the modulator.

[0152] Step 702: The service module transmits the service electrical sequence to the modulator.

[0153] Step 703: The bias controller sends the first bias control signal to the I channel of the modulator.

[0154] For an explanation of the execution process of steps 701 to 703 shown in this embodiment, please refer to steps 201 to 203 in Figure 2, which will not be described in detail here.

[0155] Step 704: The bias controller sends a second bias control signal to the Q path of the modulator.

[0156] In this embodiment, to control the bias point of the P-channel at the third target bias point, the bias controller sends a second bias control signal to the Q-channel. Specifically, this second bias control signal includes a second bias signal, a third target signal, and a fourth target signal. The third and fourth target signals are obtained by superimposing a disturbance signal onto the second bias signal. It can be understood that the second bias control signal includes a second bias signal without the added disturbance signal, and third and fourth target signals with the added disturbance signal.

[0157] The bias controller shown in this embodiment sends multiple pairs of sub-control signals to the I and Q channels. Each pair of sub-control signals includes one of a first target signal and a second target signal, and also includes one of a third target signal and a fourth target signal. For example, the multiple pairs of sub-control signals include a first pair of control signals, a second pair of control signals, a third pair of control signals, and a fourth pair of control signals. This embodiment does not limit the number of the first pair of control signals, the second pair of control signals, the third pair of control signals, and the fourth pair of control signals.

[0158] The first pair of control signals includes a first target signal and a third target signal; the second pair of control signals includes a second target signal and a fourth target signal; the third pair of control signals includes a first target signal and a third target signal; and the fourth pair of control signals includes a second target signal and a fourth target signal. The voltage of the first target signal is the sum of the voltage of the first bias signal and the voltage of the first disturbance signal; the voltage of the second target signal is the sum of the voltage of the first bias signal and the voltage of the second disturbance signal. For a detailed explanation, please refer to the description of the first and second target signals corresponding to Figure 2; further details will not be elaborated here. To obtain the third target signal, the bias controller superimposes a third perturbation signal onto the second bias signal to obtain the third target signal. To obtain the fourth target signal, the bias controller superimposes a fourth perturbation signal onto the second bias signal to obtain the fourth target signal. For a description of the second bias signal and the superposition of the third perturbation signal onto the second bias signal to obtain the third target signal, please refer to the description of superimposing the first perturbation signal onto the first bias signal to obtain the first target signal. For a description of superimposing the fourth perturbation signal onto the second bias signal to obtain the fourth target signal, please refer to the description of superimposing the second perturbation signal onto the first bias signal to obtain the second target signal. Specific details will not be repeated here. In this embodiment, the absolute value of the third perturbation signal voltage remains unchanged during the duration of the third perturbation signal, and the absolute value of the fourth perturbation signal voltage remains unchanged during the duration of the fourth perturbation signal. The bias controller sends the same pair of target signals to both the I-channel and Q-channel within the same time period. See Figure 8, which is an example diagram of a first embodiment of the control of the P-channel bias point provided in this application.

[0159] Example 1: During the first disturbance period (time t3 to time t4), the bias controller sends a first pair of control signals to channel I. This first pair of control signals includes a first target signal and a third target signal. The voltage of the first target signal is the sum of the voltage Vd0 of the first bias signal and the voltage Vd1 of the first disturbance signal. During the second disturbance period (time t3 to time t4), the bias controller sends the third target signal from this first pair of control signals to channel Q. In this example, the voltage of the third target signal is the sum of the voltage Vf0 of the second bias signal and the voltage Vf1 of the third disturbance signal. In this example, the first disturbance signal voltage Vd1 and the third disturbance signal voltage Vf1 corresponding to the first pair of control signals have the same polarity and are both positive, for example, both are 0.2V. This embodiment takes an example where both the voltage of the first bias signal and the voltage of the second bias signal are 3V; therefore, the voltages of the first target signal and the third target signal in the first pair of control signals are both 3.2V.

[0160] Example 2: During the first disturbance period (t7 to t8), the bias controller sends the second target signal and the fourth target signal from the second pair of sub-control signals to the I-channel. In this example, the second target signal is the sum of the voltage Vd0 of the first bias signal and the voltage Vd2 of the second disturbance signal. During the second disturbance period (t7 to t8), the bias controller sends the voltage of the fourth target signal from the second pair of sub-control signals to the Q-channel. In this example, the voltage of the fourth target signal is the sum of the voltage Vf0 of the second bias signal and the voltage Vf1 of the fourth disturbance signal. The polarities of the second disturbance signal voltage Vd2 and the fourth disturbance signal voltage Vf1 corresponding to the second pair of control signals in this example are opposite, and the absolute value of the second disturbance signal voltage Vd2 is equal to the absolute value of the fourth disturbance signal voltage Vf1. For example, the second disturbance signal voltage Vd2 is negative (e.g., -0.2V), and the fourth disturbance signal voltage Vf1 is positive (e.g., 0.2V). Therefore, the voltage of the second target signal is -2.8V, and the voltage of the fourth target signal is 3.2V.

[0161] Example 3: During the first disturbance period (time t11 to time t12), the bias controller sends the first target signal from the third pair of sub-control signals to the I-channel. In this example, the voltage of the first target signal is the sum of the voltage Vd0 of the first bias signal and the voltage Vd1 of the first disturbance signal. During the second disturbance period (time t11 to time t12), the bias controller sends the third target signal from the third pair of sub-control signals to the Q-channel. In this example, the voltage of the third target signal is the sum of the voltage Vf0 of the second bias signal and the voltage Vf2 of the third disturbance signal. The first disturbance signal voltage Vd1 and the third disturbance signal voltage Vf2 corresponding to the third pair of control signals in this example have opposite polarities; that is, the first disturbance signal voltage Vd1 is positive (e.g., 0.2V), and the third disturbance signal voltage Vf2 is negative (e.g., -0.2V). Therefore, the voltage of the first target signal is 3.2V, and the voltage of the third target signal is -2.8V.

[0162] Example 4: During the first disturbance period (t15 to t16), the bias controller sends the second target signal from the fourth pair of sub-control signals to the I-channel. In this example, the fourth target signal is the sum of the first bias signal Vd0 and the second disturbance signal voltage Vd2. During the second disturbance period (t15 to t16), the bias controller sends the fourth target signal from the fourth pair of sub-control signals to the Q-channel. In this example, the voltage of the fourth target signal is the sum of the second bias signal Vf0 and the fourth disturbance signal voltage Vf2. The second disturbance signal voltage Vd2 and the fourth disturbance signal voltage Vf2 corresponding to the second pair of control signals in this example have the same polarity and are both negative; for example, both the second disturbance signal voltage Vd2 and the fourth disturbance signal voltage Vf2 are -0.2V. Therefore, the voltage of the second target signal is -2.8V, and the voltage of the fourth target signal is -2.8V.

[0163] For an explanation of the first bias signal Vd0 and the second bias signal Vf0 shown in the above example, please refer to the corresponding description in Figure 2, which will not be repeated here. This embodiment takes the overlap of the first and second disturbance time periods corresponding to the same pair of target signals by the bias controller as an example (see the example above). Therefore, the bias controller can send the same pair of target signals to both the I and Q channels within the same time period without limitation. Alternatively, the first and second disturbance time periods corresponding to the same pair of target signals by the bias controller can partially overlap, as long as there is a time interval between the first disturbance time period and the service time period, and a time interval between the second disturbance time period and the service time period. For an explanation of the service time period, please refer to the corresponding description in Figure 2, which will not be repeated here.

[0164] This embodiment illustrates an example where the absolute values ​​of the voltages of the first, second, third, and fourth disturbance signals are all equal. For instance, in the example shown in Figure 8, the voltages of the first disturbance signal corresponding to the first pair of control signals are: Vd1 = 0.2V, Vf1 = 0.2V; the voltages of the second disturbance signal corresponding to the second pair of control signals are: Vd2 = -0.2V, Vf1 = 0.2V; the voltages of the third disturbance signal corresponding to the third pair of control signals are: Vd1 = 0.2V, Vf2 = -0.2V; and the voltages of the fourth disturbance signal corresponding to the fourth pair of control signals are: Vd2 = -0.2V, Vf2 = -0.2V. Therefore, the absolute values ​​of the voltages of the first, second, third, and fourth disturbance signals are all equal to 0.2V. Using the voltage examples of the various disturbance signals shown in this embodiment, the control accuracy and efficiency can be effectively improved. It should be noted that the description of the voltage value relationship between the various disturbance signals in this embodiment is an optional example and is not limited. As long as the bias controller can achieve the purpose of controlling the P-path bias point to the third target bias point based on the various disturbance voltages, it is acceptable.

[0165] During the time interval between two adjacent service time periods, the bias controller sends at least one of the following to the I-path and Q-path:

[0166] At least one first pair of control signals, at least one second pair of control signals, at least one third pair of control signals, and at least one fourth pair of control signals.

[0167] For example, the time interval between the service period from time t1 to time t2 and the service period from time t5 to time t6 includes a first pair of control signals; the time interval between the service period from time t5 to time t6 and the service period from time t9 to time t10 includes a second pair of control signals; the time interval between the service period from time t5 to time t6 and the service period from time t9 to time t10 includes a third pair of control signals; and the time interval between the service period from time t9 to time t10 and the service period from time t13 to time t14 includes a fourth pair of control signals.

[0168] Step 705: The I-path of the modulator modulates the first sub-optical signal into the first service optical signal.

[0169] For an explanation of the execution process of step 705 in this embodiment, please refer to step 204 in Figure 2, which will not be elaborated further.

[0170] Step 706: The Q path of the modulator modulates the second sub-optical signal into the second service optical signal.

[0171] For an explanation of the execution process of step 706 in this embodiment, please refer to step 207 in Figure 2, which will not be elaborated further.

[0172] Step 707: The I-path of the modulator modulates the first sub-optical signal into the target detection light.

[0173] Step 708: The Q path of the modulator modulates the second sub-optical signal into target detection light.

[0174] Specifically, when the modulator's I-path receives a first target signal from the bias controller, the I-path modulates a first sub-optical signal according to the first target signal to obtain a first target detection light. When the modulator's I-path receives a second target signal from the bias controller, the I-path modulates the first sub-optical signal according to the second target signal to obtain a second target detection light. It can be understood that the target detection light output from the I-path specifically includes both the first target detection light and the second target detection light.

[0175] When the modulator's Q-path receives a third target signal from the bias controller, the I-path modulates the second sub-optical signal according to the third target signal to obtain the third target detection light. When the modulator's Q-path receives a fourth target signal from the bias controller, the Q-path modulates the second sub-optical signal according to the fourth target signal to obtain the fourth target detection light. It can be understood that the target detection light output by the Q-path specifically includes both the third and fourth target detection lights.

[0176] Step 709: The bias controller sends a third bias signal to the P-channel.

[0177] In this embodiment, taking the requirement for P-path to operate at the +quad point as an example, the bias controller has obtained the bias voltage of the third bias signal in advance for P-path to operate at the +quad point. In order to achieve the modulation of P-path, the bias controller sends the third bias signal to P-path to control the bias point of P-path at the +quad point.

[0178] Step 710: The P-path of the modulator modulates the optical signal from the I-path and the optical signal from the Q-path to obtain the modulated optical signal.

[0179] The optical signals transmitted from channel I to channel P include first service light (see step 705) and target detection light (see step 707), while the optical signals transmitted from channel Q to channel P include second service light (see step 706) and target detection light (see step 708). Channel P, operating at the +quad point, combines the optical signals from channel I and channel Q and performs phase modulation to obtain a modulated optical signal, thereby improving channel capacity.

[0180] The modulated optical signal output from the P-path of the modulator shown in this embodiment includes a service signal and a detection signal. The service signal includes multiple sub-service signals, and the detection signal includes multiple sub-detection signals. More specifically, within the same service time period, the first service optical signal output from the I-path and the second service optical signal output from the Q-path are combined and phase-modulated by the P-path to obtain corresponding sub-service signals. For example, as shown in Figure 8, when I and Q paths send the first and second service optical signals to P path during the same service time period (e.g., time t1 to time t2), P path performs beam combining and phase modulation to obtain sub-service signal 801. When I and Q paths send the first and second service optical signals to P path during the same service time period (e.g., time t5 to time t6), P path performs beam combining and phase modulation to obtain sub-service signal 802. When I and Q paths send the first and second service optical signals to P path during the same service time period (e.g., time t9 to time t10), P path performs beam combining and phase modulation to obtain sub-service signal 803. When I and Q paths send the first and second service optical signals to P path during the same service time period (e.g., time t13 to time t14), P path performs beam combining and phase modulation to obtain sub-service signal 804.

[0181] During the same time period (e.g., from time t3 to time t4), when the I-path and Q-path receive the first pair of sub-control signals, the I-path outputs the first target detection light and the Q-path outputs the third target detection light. The first and third target detection lights are then combined and phase-modulated by the P-path to obtain the corresponding sub-detection signal 811. During the same time period (e.g., from time t7 to time t8), when the I-path and Q-path receive the second pair of sub-control signals, the I-path outputs the second target detection light and the Q-path outputs the fourth target detection light. The second and fourth target detection lights are then combined and phase-modulated by the P-path to obtain the corresponding sub-detection signal 812. During the same time period (e.g., from time t11 to time t12), when the I-path and Q-path receive the third pair of sub-control signals, the I-path outputs the first target detection light and the Q-path outputs the third target detection light. The first and third target detection lights are then combined and phase-modulated by the P-path to obtain the corresponding sub-detection signal 813. During the same time period (e.g., from time t15 to time t16), the I-path and Q-path receive the fourth pair of sub-control signals. The I-path outputs the second target detection light and the Q-path outputs the fourth target detection light. The second target detection light and the fourth target detection light are combined and phase-modulated by the P-path to obtain the corresponding sub-detection signal 814.

[0182] In this embodiment, the modulated optical signal corresponds to one of the sub-service signal and the sub-detection signal at the same time. It can be understood that the sub-service signal and the sub-detection signal appear in a time-division multiplexing manner within the modulated optical signal. For example, the modulated optical signal corresponds to sub-service signal 801 during the time period from time t1 to time t2, and to sub-detection signal 811 during the time period from time t3 to time t4. The modulated optical signal shown in this embodiment also includes idle light. For an explanation of idle light, please refer to the description corresponding to Figure 2, which will not be elaborated further.

[0183] Step 711: The modulator sends the modulated optical signal to the beam splitter.

[0184] Step 712: After the optical signal is split and modulated by the beam splitter, a first beam split signal and a second beam split signal are obtained. The first beam split signal is sent to the processor, and the second beam split signal is output.

[0185] For an explanation of the execution process of steps 711 to 712 shown in this embodiment, please refer to steps 211 to 212 in Figure 2. Detailed explanations will not be repeated here.

[0186] Step 713: The processor sends a third bias adjustment command to the bias controller.

[0187] The processor can perform an FFT on the digital signal to extract the first harmonic amplitude S1 and the second harmonic amplitude S2. If the bias point of the P-channel needs to be controlled at +quad or -quad, the first harmonic amplitude must be extremely large, and the second harmonic amplitude extremely small. The processor obtains the bias voltage adjustment amount ΔV based on the detected first harmonic amplitude S1 and second harmonic amplitude S2. The processor sends a third bias adjustment command to the bias controller, which indicates the voltage adjustment amount ΔV of the bias signal. The bias controller adjusts the magnitude of the third bias signal voltage according to the third bias adjustment command and sends the adjusted third bias signal to the P-channel until the bias point of the P-channel is precisely controlled at +quad.

[0188] As shown in this embodiment, the service module sends a service electrical signal to the modulator during the service time period, and sends two target signals from the same pair of target signals to the I channel during the first disturbance time period and to the Q channel during the second disturbance time period, respectively. There are time intervals between the service time period and the first disturbance time period, and between the service time period and the second disturbance time period. This ensures that the modulated optical signal output by the modulator corresponds to one of the service signal and the detection signal at the same time. It can be understood that the service signal and the detection signal appear in the modulated optical signal in a time-division manner, which effectively avoids crosstalk between the detection signal and the service signal, and effectively avoids the situation where the service electrical signal sent to the modulator is mixed with each target signal. While avoiding crosstalk between each target signal and the service modulation, it can improve the amplitude of the voltage used to obtain each target signal (i.e., the voltage of the first disturbance signal, the voltage of the second disturbance signal, the voltage of the third disturbance signal, and the voltage of the fourth disturbance signal mentioned above), thereby improving the accuracy and efficiency of controlling the bias point of the P channel at the third target bias point.

[0189] Figure 9 is a flowchart of the fourth embodiment of the modulator bias control method provided in this application. The difference between this embodiment and the embodiment shown in Figure 2 is that the target signal sent by the bias controller to the modulator is different, as detailed below:

[0190] Step 901: The light source sends an optical signal to the modulator.

[0191] Step 902: The service module transmits the service electrical sequence to the modulator.

[0192] For an explanation of the execution process of steps 901 to 902 in this embodiment, please refer to steps 201 to 202 in Figure 2, which will not be described in detail here.

[0193] Step 903: The bias controller sends a first bias control signal, including a first bias signal and a target signal, to the I-channel of the modulator. The amplitude of the target signal is a sine wave or a cosine wave.

[0194] The first bias control signal shown in this embodiment includes a first bias signal and a target signal. The target signal is obtained by superimposing a disturbance signal on the first bias signal. For an explanation of the relationship between the first bias control signal, the first bias signal and the target signal, please refer to step 203 in Figure 2. The specific details will not be repeated. The difference is that the target signal shown in this embodiment is different from the target signal in Figure 2.

[0195] In this embodiment, the amplitude of the target signal voltage superimposed with the first disturbance signal is a sine wave or a cosine wave. For example, as shown in Figure 10, Figure 10 is an example diagram of a second embodiment of the control I-channel bias point provided in this application. The bias controller sends the target signal to the modulator during a continuous first loading time period (e.g., time t3 to time t4). The amplitude of the target signal changes continuously during the first loading time period (e.g., time t3 to time t4), and the amplitude of the target signal is a sine wave or a cosine wave. The peak of the target signal can be 3.2V, and the trough can be 2.8V; the specific magnitude is not limited. Specifically, the bias controller sends the target signal to the I-channel during the first loading time period (time t3 to time t4). The intersection of the first loading time period and the service time period is empty. For a detailed explanation, please refer to the description corresponding to Figure 2, which will not be repeated here. This embodiment does not limit the number of cycles of the sine wave included in the first loading time period. It is understood that the example shown in Figure 10 takes the waveform of the target signal itself as a sine wave or cosine wave as an example. In this embodiment, the number of first loading time periods is one or more, and the target signal is a sine wave or cosine wave in each first loading time period. In other examples, the first loading time period includes multiple target signals, and the multiple target signals are discrete. Then, there is a time interval between two adjacent target signals. In a first loading time period, the line connecting the amplitudes of multiple target signals is a sine wave or cosine wave. Specifically, the line connecting the amplitudes of multiple target signals means that the amplitudes of the target signals at different times are connected sequentially in a first loading time period, and the resulting curve shape is a sine wave or cosine wave.

[0196] Figure 10 illustrates an example where the target signal between two adjacent service time periods exhibits at least one complete sine or cosine wave period. Figure 11 further illustrates a third embodiment of the control I-channel bias point provided in this application. The bias controller sends the target signal to the modulator during each of a discrete plurality of second loading time periods. For example, the discrete plurality of second loading time periods may include a second loading time period from time t3 to time t4 and another second loading time period from time t7 to time t8. The bias controller sends one target signal to the I-channel during the second loading time period from time t3 to time t4 and another target signal to the I-channel during the second loading time period from time t7 to time t8. Figure 11 shows a target signal sent by a bias controller during one second loading time period that is a portion of a complete sine or cosine wave. For example, during the second loading time period from time t3 to time t4, the target signal sent by the bias controller to the I-channel is a part of a complete sine wave. During the second loading time period from time t7 to time t8, the target signal sent by the bias controller to the I-channel is another part of a complete sine wave. Therefore, the line connecting the amplitudes of multiple target signals forms a complete sine wave. Specifically, by sequentially connecting the amplitudes of the target signals at different times within multiple second loading time periods, the resulting curve is a sine wave. Figure 11 shows an example where the amplitude of the line connecting multiple target signals forms a complete sine wave. In other examples, the amplitude of the line connecting multiple target signals can also form a complete cosine wave.

[0197] Figure 11 shows an example where each target signal transmitted to the I-channel has a specific waveform. Specifically, the voltage value changes continuously within the duration of a single target signal, without limitation. Alternatively, the voltage may remain constant within the duration of a single target signal, but differ between different target signals. Figure 12 is an example diagram of a fourth embodiment of the control I-channel bias point provided in this application. Figure 12 shows multiple discrete target signals transmitted to the I-channel during two adjacent second loading time periods. For example, during the second loading time period from time t3 to time t4, the bias controller sends multiple discrete target signals to the I-channel. Similarly, during the second loading time period from time t7 to time t8, the bias controller sends multiple discrete target signals to the I-channel. In this example, the line connecting the amplitudes of the multiple target signals forms a complete sine wave or cosine wave. Specifically, by sequentially connecting the amplitudes of the target signals at different times within multiple second loading time periods, the resulting curve shape is a sine wave or cosine wave. This embodiment does not limit the number of second loading time periods.

[0198] Step 904: The I-path of the modulator modulates the first sub-optical signal into the first service optical signal.

[0199] Step 905: The I-channel of the modulator modulates the first sub-optical signal into a detection light according to the target signal.

[0200] Step 906: The bias controller sends a second bias signal to the Q path of the modulator.

[0201] Step 907: The Q path of the modulator modulates the second sub-optical signal into the second service optical signal.

[0202] Step 908: The Q path of the modulator modulates the second sub-optical signal into the third detection light.

[0203] Step 909: The bias controller sends a third bias signal to the P-path of the modulator.

[0204] For a description of steps 904 to 909 in this embodiment, please refer to steps 204 to 209 in Figure 2. Detailed explanations will not be repeated here.

[0205] Step 910: The P-path of the modulator modulates the optical signal from the I-path and the optical signal from the Q-path to obtain the modulated optical signal.

[0206] The optical signals transmitted from channel I to channel P include a first service light (see step 904) and a detection light (see step 905), while the optical signals transmitted from channel Q to channel P include a second service light (see step 907) and a third detection light (see step 908). Channel P, operating at the +quad point, combines the optical signals from channel I and channel Q and performs phase modulation to obtain a modulated optical signal, thereby improving channel capacity.

[0207] The modulated optical signal output from the P-path of the modulator shown in this embodiment includes a service signal and a detection signal. The service signal includes multiple sub-service signals, and the detection signal includes multiple sub-detection signals. More specifically, within the same service time period, the first service light output from the I-path and the second service light output from the Q-path are combined and phase-modulated by the P-path to obtain corresponding sub-service signals. For example, as shown in Figures 10, 11, and 12, the I-path and Q-path send the first service light and the second service light to the P-path within the same service time period (e.g., time t1 to time t2). After the P-path performs combination and phase modulation, sub-service signal 1001 is obtained. Similarly, the I-path and Q-path send the first service light and the second service light to the P-path within the same service time period (e.g., time t5 to time t6). After the P-path performs combination and phase modulation, sub-service signal 1002 is obtained.

[0208] Within the same time period, the detection light output from the I-path and the third detection light output from the Q-path are combined and phase-modulated by the P-path to obtain corresponding sub-detection signals. For example, as shown in Figure 10, within the same time period (e.g., from time t3 to time t4), the detection light output from the I-path and the third detection light output from the Q-path are combined and phase-modulated by the P-path to obtain sub-detection signal 1011. Similarly, as shown in Figures 11 and 12, within the same time period (e.g., from time t3 to time t4), the detection light output from the I-path and the third detection light output from the Q-path are combined and phase-modulated by the P-path to obtain sub-detection signal 1101. Within the same time period (e.g., from time t7 to time t8), the detection light output from the I-path and the third detection light output from the Q-path are combined and phase-modulated by the P-path to obtain sub-detection signal 1102.

[0209] In this embodiment, the modulated optical signal corresponds to one of the sub-service signal and the sub-detection signal at the same time. It can be understood that the sub-service signal and the sub-detection signal appear in a time-division multiplexing manner within the modulated optical signal. For example, the modulated optical signal corresponds to the sub-service signal during the time period from time t1 to time t2, and to the sub-detection signal during the time period from time t3 to time t4. The modulated optical signal shown in this embodiment also includes idle light; a description of the idle light can be found in the description corresponding to Figure 2, and will not be elaborated further.

[0210] Step 911: The modulator sends the modulated optical signal to the beam splitter.

[0211] Step 912: After the optical signal is split and modulated by the beam splitter, a first beam split signal and a second beam split signal are obtained. The first beam split signal is sent to the processor, and the second beam split signal is output.

[0212] Step 913: The processor sends the first bias adjustment command to the bias controller.

[0213] Steps 911 to 913 in this embodiment are shown as steps 210 to 213 in Figure 2, and will not be described in detail.

[0214] In the embodiment shown in Figure 9, to achieve the purpose of controlling the I-path of the modulator at the first target bias point, the bias controller sends a second bias signal to the Q-path during the second disturbance time period. In other examples, the purpose of controlling the Q-path of the modulator at the second target bias point can also be achieved. In this case, the bias controller sends a first bias signal to the I-path during the first disturbance time period, and sends a target signal to the Q-path during the second disturbance time period. The amplitude of the target signal is a sine wave or a cosine wave, or the line connecting the amplitudes of multiple target signals is a sine wave or a cosine wave. For a detailed explanation, please refer to the description of the target signal in step 903, which will not be elaborated here. For example, to achieve the goal of controlling the P-path of the modulator at the third target bias point, during the first disturbance time period, the bias controller sends the target signal to the I-path, and during the second disturbance time period, the bias controller sends the target signal to the Q-path. The amplitudes of the target signals received by the I-path and the Q-path are sine or cosine waves, or the line connecting the amplitudes of multiple target signals is a sine or cosine wave. For a detailed explanation, please refer to the description of the target signal in step 903, which will not be repeated here. In this example, the frequency of the target signal received by the I-path is different from the frequency of the target signal received by the Q-path.

[0215] In the above embodiments, the bias controller needs to obtain in advance a first bias signal that causes the I-path of the modulator to operate at a first target bias point (e.g., null point), a second bias signal that causes the Q-path of the modulator to operate at a second target bias point (e.g., null point), and a third bias signal that causes the P-path of the modulator to operate at a third target bias point (e.g., +quad point). This embodiment does not limit the process by which the bias controller obtains the first, second, and third bias signals. For example, Figure 13 is a flowchart of the steps for obtaining the bias voltage provided in this application. Based on the flowchart shown in Figure 13, the bias controller can obtain the first, second, and third bias signals shown in the above embodiments. It can be understood that the bias voltage acquisition process shown in this embodiment is executed before executing the above method embodiments.

[0216] In existing solutions, the bias controller pre-obtains a first driving range corresponding to the I-path. The first driving range includes multiple voltages arranged in a continuous sequence. The voltages within the first driving range can drive the I-path to perform normal modulation. The bias controller also pre-obtains a second driving range corresponding to the Q-path. The second driving range includes multiple voltages arranged in a continuous sequence. The voltages within the second driving range can drive the Q-path to perform normal modulation. The bias controller also pre-obtains a third driving range corresponding to the P-path. The third driving range includes multiple voltages arranged in a continuous sequence. The voltages within the third driving range can drive the P-path to perform normal modulation. To successfully obtain the first bias signal that controls the bias point of the I-channel to the first target bias point, the second bias signal that controls the bias point of the Q-channel to the second target bias point, and the third bias signal that controls the bias point of the P-channel to the third target bias point, the bias controller needs to send voltages to the I-channel of the modulator that traverse every voltage in the first driving range, to the Q-channel of the modulator that traverse every voltage in the second driving voltage range, and to the P-channel of the modulator that traverse every voltage in the third driving voltage range, until the first, second, and third bias signals are obtained. It can be understood that this scheme has low efficiency in obtaining each bias voltage. The method shown in Figure 13 can effectively improve the efficiency of obtaining the first, second, and third bias signals.

[0217] Step 1301: The bias controller sends multiple first test signals to the I channel of the modulator.

[0218] Step 1302: The bias controller sends multiple second test signals to the Q path of the modulator.

[0219] Step 1303: The bias controller sends multiple third test signals to the P-path of the modulator.

[0220] In this embodiment, the processor sends a test command to the bias controller. This test command instructs the bias controller to send multiple first test signals to the I-channel of the modulator. These first test signals are used to obtain a first bias signal, which controls the I-channel to operate at a first target bias point, for example, null. The test command also instructs the bias controller to send multiple second test signals to the Q-channel of the modulator. These second test signals are used to obtain a second bias signal, which controls the Q-channel to operate at a second target bias point, for example, null. Furthermore, the test command instructs the bias controller to send multiple third test signals to the P-channel of the modulator. These third test signals are used to obtain a third bias signal, which controls the P-channel to operate at a third target bias point, for example, +quad.

[0221] Step 1304: The light source sends test light to the modulator.

[0222] As shown in Figures 1 and 2, the modulator includes a beam splitter that splits the test light from the light source to obtain a first test light and a second test light. The first test light is transmitted along the I path, and the second test light is transmitted along the Q path.

[0223] Step 1305: The I-path of the modulator modulates the first test light into the third test light.

[0224] Step 1306: The Q path of the modulator modulates the second test light into the fourth test light.

[0225] Step 1307: The modulator combines the third and fourth test beams in the P-path to obtain the fifth test beam, and modulates the fifth test beam into the sixth test beam.

[0226] For a description of the I-path, Q-path, and P-path modulation of the modulator, please refer to the above embodiment; further details will not be provided here.

[0227] Step 1308: The modulator's P-path sends the sixth test light to the photodetector.

[0228] Step 1309: The photodetector performs photoelectric conversion on the sixth test light to obtain the first feedback signal and sends the first feedback signal to the processor.

[0229] For a description of the photodetector and processor, please refer to the description corresponding to Figure 1, which will not be elaborated upon here.

[0230] Step 1310: The processor sends a second feedback signal to the bias controller based on the first feedback signal.

[0231] The second feedback signal shown in this embodiment is used to indicate the first bias signal, the second bias signal, and the third bias signal. Specifically, the difference between Figure 13 and the existing solutions is that the existing solutions iterate through each voltage in the driving range to the modulator, while the processor shown in this embodiment does not need to iterate through each voltage in the driving range. Instead, it pre-creates a function relationship and determines the first test signal, the second test signal, and the third test signal to be sent to the modulator based on this function relationship. Because this embodiment does not need to iterate through each voltage in the first, second, and third driving ranges to send to the modulator, but instead selects the corresponding number of first test signals, second test signals, and third test signals in the first, second, and third driving ranges according to the number of unknowns included in the function relationship. Since the first test signal, second test signal, and third test signal shown in this embodiment are not obtained through the iterative method shown in the existing solutions, the voltage difference between two adjacent first test signals sent by the bias controller to the modulator is greater than or equal to a first preset value. Similarly, among the multiple second test signals sent by the bias controller to the modulator, the voltage difference between two adjacent second test signals is greater than or equal to a second preset value. Among the multiple third test signals sent by the bias controller to the modulator, the voltage difference between two adjacent third test signals is greater than or equal to a third preset value. This embodiment does not limit the magnitude of the first, second, and third preset values. Taking the first driving range as an example, since existing solutions send voltage to the modulator through a traversal method, two adjacent first test signals sent to the modulator will be relatively close. However, this embodiment does not require sending voltage to the modulator through a traversal method, so the voltage difference between two adjacent first test signals is greater than or equal to the first preset value. This embodiment does not limit the specific functional relationship; different functional relationships can be configured according to different modulator types. For example, if the modulator only includes one channel, the functional relationship can be: Among them, A, Vπ, All parameters are unknown, P is the optical power output of the I-path, and VX is the first bias signal to be obtained. Therefore, the processor can select three first test signals within the first driving range to send to the I-path of the modulator. Based on the optical power P of the optical signal output by the I-path obtained by the photodetector for each transmitted first test signal, the voltage Vπ of the first bias signal can be obtained by sending the three first test signals to the I-path. It can be understood that for the I-path of the modulator, the processor does not need to traverse all voltages within the first driving range and send them to the I-path, but only needs to select a specific number of first test signals according to the number of unknown parameters in the function, thus improving the efficiency of controlling the bias point of the I-path at the first target bias point. For an explanation of controlling the bias point of the Q-path at the second target bias point and the bias point of the P-path at the third target bias point, please refer to the explanation of controlling the bias point of the I-path at the first target bias point; details will not be repeated here.

[0232] Regarding the above method embodiments, it should be noted that:

[0233] (1) The step numbers of the flowcharts described in the embodiments are only examples of the execution flow and do not constitute a restriction on the order of execution of the steps. There is no strict execution order between steps that have no temporal dependency relationship with each other in the embodiments of this application. In addition, not all steps shown in the flowcharts are mandatory steps. Some steps can be added or deleted based on the actual needs of each flowchart.

[0234] (2) In the various embodiments of this application, unless otherwise specified or logically conflicting, the terms and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0235] The methods provided by the embodiments of this application have been described in detail above. The apparatus and chip provided by the embodiments of this application will be described in detail below. It should be understood that the descriptions of the apparatus embodiments correspond to the descriptions of the method embodiments; therefore, any content not described in detail can be referred to the method embodiments above, and for the sake of brevity, will not be repeated here.

[0236] This application provides an optical device, as shown in Figure 1, but without limitation. For example, the optical device provided in this embodiment can also be applied to the field of sensing. Figure 14 is a structural example diagram of an embodiment of the optical device provided in this application. Specifically, for example, the optical device shown in this embodiment can be applied to the field of distributed fiber-optic acoustic sensors (DAS) to achieve applications such as oil and gas resource exploration, oil and gas pipeline monitoring, and railway track monitoring.

[0237] The optical device 1400 shown in this embodiment includes a light source 101, a modulator 103, a beam splitter 104, a photodetector 106, a bias controller 107, a service module 108, an analog-to-digital converter 109, and a processor 120. For detailed descriptions, please refer to Figure 1, which will not be repeated here. The optical device 1400 also includes a coupler 1401 connected between the light source 101 and the modulator 103, and an amplitude modulator 1404 connected between the circulator 1402 and the beam splitter. The amplitude modulator 1404 is also connected to the service module 108. The optical device 1400 further includes an optical receiver 1403 connected to the circulator 1402 and the processor 120. The optical receiver 1403 is also connected to the coupler 1401. After receiving the optical signal from the light source 101, the coupler 1401 splits the optical signal into a modulated optical signal and a local light. When the modulator 103 receives the modulated optical signal from the coupler 1401, it modulates the modulated optical signal to output a modulated optical signal. For a description of the modulator 103 outputting the modulated optical signal, please refer to any of the above method embodiments; specific details will not be repeated here. The beam splitter 104 splits the modulated optical signal from the modulator 103 to obtain a first split signal and a second split signal. When the photodetector 106 receives the first split signal from the beam splitter 104, it performs photoelectric conversion on the first split signal to obtain a detection electrical signal. The digital-to-analog converter 109 performs analog-to-digital conversion on the detection electrical signal. The processor 120 controls the voltage of the bias signal sent by the bias controller 107 to the modulator 103 based on the digital signal from the digital-to-analog converter 109. For a description of the specific process, please refer to any of the above method embodiments; specific details will not be repeated here. When the amplitude modulator 1404 receives the second split signal from the beam splitter 104, it can eliminate or suppress idle light in the second split signal. For details, please refer to the above method embodiment, which will not be repeated here. After the amplitude modulator 1404 sends the second split signal that has eliminated or suppressed idle light to the circulator 1402, the circulator 1402 inputs the second split signal into a medium. In this example, the medium is taken as an optical fiber, but it is not limited. For example, the medium can also be any medium such as air as a sensor. Each detection point in the medium can return echo light to the optical device according to the detection light. The echo light can be backscattered Rayleigh light. The echo light is reflected to the circulator 1402, and the circulator 1402 sends the echo light to the coherent receiver 1403. The coherent receiver 1403 beats the local light from the coupler 1401 and the echo light from the circulator 1402 and forms an electrical signal output. The processor 120 processes the electrical signal to realize detection.It should be clarified that Figure 14 uses an optical device including a modulator for the field of sensing as an example, and is not limited thereto. For example, an optical device including a modulator can also be applied to the fields of optical communication, data centers, LiDAR (light detection and ranging), quantum communication, quantum computing, etc.

[0238] Optionally, an amplifier may be included between the circulator 1402 and the medium, or between the modulator 103 and the circulator 1402. This amplifier amplifies the optical power of the probe light to improve detection efficiency. This embodiment does not limit the type of amplifier; for example, an erbium-doped fiber amplifier may be used.

[0239] Figure 15 is a structural example diagram of an embodiment of the processing device provided in this application. The processing device 1500 shown in this embodiment specifically includes a transceiver module 1501 and a processing module 1502.

[0240] For example, the processing device 1500 shown in this embodiment can be a logic module or software in the bias controller, or it can be a component or device in the bias controller. Then, the transceiver module 1501 included in the processing device 1500 is used to execute the transceiver-related steps executed by the bias controller in the above method embodiment, and the processing module 1502 is used to execute the processing-related parts executed by the bias controller in the above method embodiment.

[0241] For example, the processing device 1500 shown in this embodiment can be a logic module or software in a processor, or it can be a component or device in a processor. Then, the transceiver module 1501 included in the processing device 1500 is used to execute the transceiver-related steps executed by the processor in the above method embodiment, and the processing module 1502 is used to execute the processing-related parts executed by the processor in the above method embodiment.

[0242] For example, the processing device 1500 shown in this embodiment can be a logic module or software in the business module, or it can be a component or device in the business module. Then, the transceiver module 1501 included in the processing device 1500 is used to execute the transceiver-related steps executed by the business module in the above method embodiment, and the processing module 1502 is used to execute the processing-related parts executed by the business module in the above method embodiment.

[0243] It should be understood that the specific process of each module performing the above-mentioned steps has been described in detail in the above method embodiments, and will not be repeated here for the sake of brevity.

[0244] Figure 16 is a structural example diagram of an embodiment of the chip provided in this application. The chip 1600 (or processing system) includes at least one processing device 1610 and an interface 1620. The processing device 1610 can be a processing circuit within the chip 1600. The processing device 1610 can be coupled to a memory unit, calling instructions from the memory unit, enabling the chip 1600 to implement the methods and functions of the various embodiments of this application. The interface 1620 can be an input / output circuit within the chip 1600, outputting processed information or inputting data or signaling information to be processed into the chip 1600 for processing. It is understood that the interface 1620 is used to implement signal transmission between at least one processing device 1610 and an external source. Optionally, the processing device 1610 can be implemented by one or more processors, including the one or more processors or the processing portion within the one or more processors. Optionally, the interface 1620 can include transceiver circuits, network interface cards, input / output circuits, or communication interfaces, etc. The interface 1620 can provide program instructions to the processing device 1610, which executes the program instructions to implement the function of the bias controller shown in the above method embodiment. Alternatively, the processing device 1610 can have a fixed hardware circuit, which it uses to implement the function of the bias controller shown in the above method embodiment.

[0245] As one option, the chip 1600 is used to implement operations performed by at least one of the bias controller, processor, and service module in the various method embodiments described above.

[0246] Specifically, the processing device 1610 is used to implement the processing-related operations performed by at least one of the bias controller, processor, and service module in the above method embodiment; the interface 1620 is used to implement the sending and / or receiving-related operations performed by at least one of the bias controller, processor, and service module in the above method embodiment.

[0247] Optionally, the chip 1600 may also include the modulator shown in the above embodiments.

[0248] Optionally, chip 1600 may also include the light source shown in the above embodiments.

[0249] This application also provides a computer-readable storage medium storing computer instructions for implementing the methods executed by at least one of the bias controller, processor, and service module in the above-described method embodiments.

[0250] For example, when the computer program is executed by a computer, the computer can implement the method executed by at least one of the bias controller, processor, and business module in the various embodiments of the above method.

[0251] This application also provides a computer program product comprising instructions which, when executed by a computer, implement the methods described above, executed by at least one of a bias controller, a processor, and a business module.

[0252] This application also provides an optical network, which includes one or more optical devices. For a description of the optical devices, please refer to the descriptions corresponding to Figure 1 or Figure 14, which will not be elaborated further.

[0253] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A bias control method for a modulator, characterized in that, The method includes: The bias controller sends a bias control signal to the modulator. The bias control signal includes a bias signal and a target signal. The target signal is obtained by superimposing a disturbance signal on the bias signal. During the time period when the modulator outputs a service signal, the modulator receives the bias signal. During the time period when the modulator outputs a detection signal, the modulator receives the target signal. The detection signal is used to control the bias point of the modulator at the target bias point.

2. The method according to claim 1, characterized in that, There is a time interval between the time period during which the modulator outputs the service signal and the time period during which it outputs the detection signal.

3. The method according to claim 1 or 2, characterized in that, The bias signal includes a first bias signal, the bias control signal includes a first bias control signal, and the bias controller sends the bias control signal to the modulator including: The bias controller sends the first bias control signal to the first branch of the modulator. The first bias control signal includes the first bias signal, the first target signal, and the second target signal. The first target signal is obtained by superimposing the first bias signal with the first disturbance signal. The second target signal is obtained by superimposing the first bias signal with the second disturbance signal. The polarity of the voltage of the first disturbance signal is opposite to that of the voltage of the second disturbance signal.

4. The method according to claim 3, characterized in that, The voltage of the first target signal is the sum of the voltage of the first bias signal and the voltage of the first disturbance signal, and the voltage of the second target signal is the sum of the voltage of the first bias signal and the voltage of the second disturbance signal.

5. The method according to claim 3 or 4, characterized in that, Between two adjacent service signals output by the modulator, the modulator receives at least one of the following: At least one of the first target signals, or at least one of the second target signals.

6. The method according to any one of claims 3 to 5, characterized in that, During the duration of the first disturbance signal, the voltage of the first disturbance signal remains unchanged; during the duration of the second disturbance signal, the voltage of the second disturbance signal remains unchanged; and the absolute value of the voltage of the first disturbance signal is equal to the absolute value of the voltage of the second disturbance signal.

7. The method according to any one of claims 3 to 6, characterized in that, The method further includes: The bias controller sends a second bias signal to the second branch of the modulator. During the time period when the modulator outputs the service signal and during the time period when the modulator outputs the detection signal, the second branch receives the second bias signal.

8. The method according to any one of claims 3 to 6, characterized in that, The bias signal includes a second bias signal, the bias control signal includes a second bias control signal, and the bias controller sends the bias control signal to the modulator including: The bias controller sends a second bias control signal to the second branch of the modulator. The second bias control signal includes a second bias signal, a third target signal, and a fourth target signal. The third target signal is obtained by superimposing a third disturbance signal on the second bias signal, and the fourth target signal is obtained by superimposing a fourth disturbance signal on the second bias signal. The time period during which the bias controller sends the first target signal to the first branch overlaps at least partially with the time period during which it sends the third target signal to the second branch, and the time period during which the bias controller sends the second target signal to the first branch overlaps at least partially with the time period during which it sends the fourth target signal to the second branch.

9. The method according to claim 8, characterized in that, During the duration of the third disturbance signal, the absolute value of the third disturbance signal voltage remains unchanged; during the duration of the fourth disturbance signal, the absolute value of the fourth disturbance signal voltage remains unchanged; and the absolute value of the third disturbance signal voltage is equal to the absolute value of the fourth disturbance signal voltage.

10. The method according to claim 8 or 9, characterized in that, The absolute value of the first disturbance signal voltage is equal to the absolute value of the third disturbance signal voltage, and the absolute value of the second disturbance signal voltage is equal to the absolute value of the fourth disturbance signal voltage.

11. The method according to any one of claims 8 to 10, characterized in that, Between two adjacent service signals output by the modulator, the bias controller sends at least one of the following to the modulator: At least one of the third target signals, or at least one of the fourth target signals.

12. The method according to any one of claims 8 to 11, characterized in that, The bias control signals include a first pair of control signals, a second pair of control signals, a third pair of control signals, and a fourth pair of control signals. The first pair of control signals includes a first target signal superimposed with a first disturbance signal of positive polarity, and a third target signal superimposed with a third disturbance signal of positive polarity. The second pair of control signals includes a second target signal superimposed with a second disturbance signal of negative polarity, and a fourth target signal superimposed with a fourth disturbance signal of positive polarity. The third pair of control signals includes a first target signal superimposed with a first disturbance signal of positive polarity, and a third target signal superimposed with a third disturbance signal of negative polarity. The fourth pair of control signals includes a second target signal superimposed with a second disturbance signal of negative polarity, and a fourth target signal superimposed with a fourth disturbance signal of negative polarity.

13. The method according to claim 1 or 2, characterized in that, The bias controller sends the target signal to the modulator in each of the first loading time periods in at least one first loading time period, the amplitude of the target signal being continuously variable within the first loading time period, and the amplitude of the target signal being a sine wave or a cosine wave. or, The bias controller sends the target signal to the modulator in each of the plurality of second loading time periods, with a time interval between two adjacent second loading time periods, and the line connecting the amplitudes of the plurality of target signals is a sine wave or a cosine wave.

14. A bias control method for a modulator, characterized in that, The method includes: The modulator receives a bias control signal, which includes a bias signal and a target signal. The target signal is obtained by superimposing a disturbance signal on the bias signal. During the time period when the modulator outputs a service signal, the modulator receives the bias signal. During the time period when the modulator outputs a detection signal, the modulator receives the target signal. The detection signal is used to control the bias point of the modulator at the target bias point.

15. The method according to claim 14, characterized in that, The method further includes: The modulator receives a service electrical sequence, which includes multiple service electrical signals, and there is a time interval between any two adjacent service electrical signals. After the modulator receives the bias control signal, the method further includes: The modulator modulates the optical signal into the service signal according to the bias signal and the service electrical signal; The modulator modulates the optical signal into the detection signal according to the target signal.

16. The method according to claim 14 or 15, characterized in that, There is a time interval between the time period during which the modulator outputs the service signal and the time period during which it outputs the detection signal.

17. The method according to any one of claims 14 to 16, characterized in that, The bias signal includes a first bias signal, the bias control signal includes a first bias control signal, the target signal includes a first target signal and a second target signal, the voltage of the first target signal is not equal to the voltage of the second target signal, and the modulator receives the bias control signal including: The first branch of the modulator receives the first bias control signal, which includes the first bias signal, the first target signal, and the second target signal.

18. The method according to claim 17, characterized in that, The method further includes: The second branch of the modulator receives the second bias signal. During the time period when the modulator outputs the service signal and during the time period when the modulator outputs the detection signal, the second branch receives the second bias signal.

19. The method according to claim 17, characterized in that, The bias signal includes a second bias signal, the bias control signal includes a second bias control signal, the target signal includes a third target signal and a fourth target signal, and the modulator receives the bias control signal including: The second branch of the modulator receives the second bias control signal, which includes the second bias signal, the third target signal, and the fourth target signal. The time period during which the first branch receives the first target signal at least partially overlaps with the time period during which the second branch receives the third target signal, and the time period during which the first branch receives the second target signal at least partially overlaps with the time period during which the second branch receives the fourth target signal.

20. The method according to any one of claims 14 to 16, characterized in that, The bias controller sends the target signal to the modulator in each of the first loading time periods in at least one first loading time period, the amplitude of the target signal being continuously variable within the first loading time period, and the amplitude of the target signal being a sine wave or a cosine wave. or, The bias controller sends the target signal to the modulator in each of the plurality of second loading time periods, with a time interval between two adjacent second loading time periods, and the line connecting the amplitudes of the plurality of target signals is a sine wave or a cosine wave.

21. A bias control method for a modulator, characterized in that, The method includes: The bias controller sends a bias control signal to the modulator. The bias control signal includes a bias signal and a target signal. The target signal is obtained by superimposing a disturbance signal on the bias signal. The modulator receives the bias control signal. During the time period when the modulator outputs the service signal, the modulator receives the bias signal. During the time period when the modulator outputs the detection signal, the modulator receives the target signal. The detection signal is used to control the bias point of the modulator at the target bias point.

22. An optical device, characterized in that, The method includes a modulator and a bias controller, the bias controller being configured to implement the method as claimed in any one of claims 1 to 13, and the modulator being configured to implement the method as claimed in any one of claims 14 to 20.

23. The optical device according to claim 22, characterized in that, The optical device also includes a light source for sending optical signals to the modulator.

24. A processing apparatus, characterized in that, Includes a module for performing the method according to any one of claims 1 to 13.

25. A chip, characterized in that, It includes at least one processing device and an interface, the interface being used to enable signal transmission between the at least one processing device and an external source, the at least one processing device being used to implement the method of any one of claims 1 to 13.

26. The chip according to claim 25, characterized in that, The chip further includes a modulator connected to the processing device, the modulator being configured to implement the method as described in any one of claims 14 to 20.

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